While you wait for a proper historian's answer, I can provide you some basic details as a canarian myself. A small correction, guanche refers to aboriginals of Tenerife, while other islands receive different names. Some myths and legends show that there was contact between the islands, like the legend of Garajonay, but it seems like contact between the islands was fairly limited. Also the seafaring capabilities of the aboriginals were very limited, so cultures varied somewhat.

The conquest of the islands was done by different means in the almost 100 years long period that it took. Notably using french soldiers from Betancourt in Lanzarote and Fuerteventura. On a side note, Bethencourt/Betancor and another hundred variations are still very common surnames in the islands

The spanish did certainly export many strategies and techniques learned or tested in the Canary Islands to the Americas. Some examples include the architecture style used. This architecture style pioneered in the canary islands has been recognized as a UNESCO as world heritage site in the town of La Laguna in Tenerife, as a precursor of the colonial architecture used in the Americas. Another example is the development of the "ingenio" type of sugar cane plantations, which was used in the town now known as Ingenio in Gran Canaria.

The Canary islands had been inhabited for a long time, likely by different waves of people. There are some glyphs but nothing similar to a written history so the only remaining primary sources are from the spanish themselves. It is possible that many cultural traits had been gained and lost with time during the centuries, for example the now UNESCO world heritage site of Cuevas Caídas in Gran Canaria was some sort of calendar or temple but it was being used as a place to keep goats by the time the spanish arrived, so we can only guess it's purpose.

The aboriginals lived in stratified neolitical societies (metals are scarce so metal working never appeared) where violent clashes were common, as evidenced by the many fortresses and other defensive structures found in the islands, such as the fortress of Ansite or the wall dividing Fuerteventura in 2 halves. When the spanish came they attempted with varying success to pit different kingdoms against each other. In some occasions such as the conquest of gran canaria, they opted for using existing power structures to their advantage. The spanish captured the king (who was given the title of "guanarteme") and forced him to submit to the spanish crown, convert to christianity and was given a new name, Fernando Guanarteme. This name was chosen for being the name of the spanish king and was chosen with the intention of creating an association between the idea of Fernando and king. The king Fernando Guanarteme continued ruling the island at least nominally as an envoy of Spain.

Finally on the eradication of aboriginal canarians: their culture has been irremediably lost, with only some words surviving in the canarian dialects of spanish. The people not so much, genetical studies on modern canarians shows a very large percentage of mitochondrial dna of aboriginal origin among the islanders. This is still visible in physical traits and it might related with the larger obesity and diabetes rates in the islands compared to the rest of spain. In Y cromosome dna only trace amounts have been found, which point towards the assimilation of women and death of the male population. There were instances in which the aboriginals pushed back and defeated the spanish, such as the siege of Ansite ("Sitio de Ansite") or the first battle of Acentejo ("Matanza de Acentejo"). But for the most part these clashes had a very one sided outcome, as the aboriginals did not even have metallic utensils and could only use sticks, stones and their knowledge of the terrain against the modern spanish army, which made heavy use of "ballesteros vizcaínos", basque crossbowmen. War, forced labor and deprivation were the most likely cause for this.

I hope this answers helps a bit, if you have any doubt I can try to help don't hesitate to reply!

Columbus had this to say in his diary about the first people he encountered in the Caribbean:

"All whom I saw were young, not above thirty years of age, well made, with fine shapes and faces; their hair short, and coarse like that of a horse's tail, combed toward the forehead, except a small portion which they suffer to hang down behind, and never cut. Some paint themselves with black, which makes them appear like those of the Canaries, neither black nor white; others with white, others with red, and others with such colors as they can find. Some paint the face, and some the whole body; others only the eyes, and others the nose. Weapons they have none, nor are acquainted with them, for I showed them swords which they grasped by the blades, and cut themselves through ignorance. They have no iron, their javelins being without it, and nothing more than sticks, though some have fish-bones or other things at the ends. They are all of a good size and stature, and handsomely formed....

It appears to me, that the people are ingenious, and would be good servants and I am of opinion that they would very readily become Christians, as they appear to have no religion. They very quickly learn such words as are spoken to them. If it please our Lord, I intend at my return to carry home six of them to your Highnesses, that they may learn our language. I saw no beasts in the island, nor any sort of animals except parrots...

At daybreak great multitudes of men came to the shore, all young and of fine shapes, very handsome; their hair not curled but straight and coarse like horse-hair, and all with foreheads and heads much broader than any people I had hitherto seen; their eyes were large and very beautiful; they were not black, but the color of the inhabitants of the Canaries, which is a very natural circumstance, they being in the same latitude with the island of Ferro in the Canaries. They were straight-limbed without exception, and not with prominent bellies but handsomely shaped." (Emphasis added)

Slavery in late medieval and early modern Iberia was not solely based on racial identity in the way that say, chattel slavery in the later English colonies was, but on non-Christian status (though the correlation of blackness and enslaved status was certainly developing rapidly). There were frequent "prisoner exchanges" between Christian and Muslim forces for ransom, and a slave held by either group could reasonably expect their condition to be temporary.

A Papal Bull issued in 1435 threatened anyone holding Canary Islanders as slaves with excommunication, because the Canary Islanders had become Christian:

"Not long ago, we learned from our brother Ferdinand, bishop at Rubicon and representative of the faithful who are residents of the Canary Islands, and from messengers sent by them to the Apostolic See, and from other trustworthy informers, the following facts: in the said islands—some called Lanzarote—and other nearby islands, the inhabitants, imitating the natural law alone, and not having known previously any sect of apostates or heretics, have a short time since been led into the Orthodox Catholic Faith with the aid of God's mercy. Nevertheless, with the passage of time, it has happened that in some of the said islands, because of a lack of suitable governors and defenders to direct those who live there to a proper observance of the Faith in things spiritual and temporal, and to protect valiantly their property and goods, some Christians (we speak of this with sorrow), with fictitious reasoning and seizing and opportunity, have approached said islands by ship, and with armed forces taken captive and even carried off to lands overseas very many persons of both sexes, taking advantage of their simplicity.Some of these people were already baptized; others were even at times tricked and deceived by the promise of Baptism, having been made a promise of safety that was not kept. They have deprived the natives of the property, or turned it to their own use, and have subjected some of the inhabitants of said islands to perpetual slavery, sold them to other persons, and committed other various illicit and evil deeds against them, because of which very many of those remaining on said islands, and condemning such slavery, have remained involved in their former errors, having drawn back their intention to receive Baptism, thus offending the majesty of God, putting their souls in danger, and causing no little harm to the Christian religion." (Sicut Dudum, 1453, emphasis added)

Enslaving Christians was wrong, and the perpetuity of their slavery was noteworthy.

By the 1450's, multiple Papal Bulls made it clear that subjugating non-Christians and enslaving them in perpetuity was the only way to save their souls, and this logic was widely applied along the Atlantic Coast of Africa (where slavery began to develop its association with specifically Sub-Saharan African identity), and later, in the Caribbean. Columbus is a prime example of how this thinking had developed by the late 15th century. As Columbus' diary makes clear, the Taíno inhabitants were physically fit to make good "servants" and would easily convert to Christianity (the justification for enslaving them in the first place).

Like in the Canary Islands, European slave raiding would quickly decimate the indigenous population of the Caribbean, and black Africans would eventually supply most of the forced labor in the region.