I always had thought that he was one of many operatives directly trained by the US government to raise an army to fight the Soviet invaders, but recently I've heard that this was not the case?
I've heard that his main motivation for 9/11 was because non-Muslim soldiers were stationed in Mecca. Is this true?
Apologies if this breaks the 20 year rule! I'm mostly wondering about 1994 and earlier, though.
I think your first question refers to the mujahideen in Afghanistan, who were a loose coalition of opposition groups to the pro-Soviet Democratic Republic of Afghanistan in the 1970s. As the backbone of the anti-Soviet insurgency, the US funneled supplies to mujahideen groups through the Pakistani intelligence service (ISI). But the insurgents received substantial support from other, non-Western groups; Osama Bin Ladin was the head of an Islamist group (Maktab al-Khidamat, or MAK) that recruited foreign fighters and raised money to support them. There's little evidence that MAK received direct funding from the American government - at any rate, the group played a very small role in the conflict, raising only $2 million and sending 100 foreign fighters to Afghanistan. Bin Laden was never directly trained or funded by the United States government - however, the CIA and ISI did directly finance Gulbuddin Hekmatyar, who was then one of the most powerful Afghani warlords. Today, he's one of the three main leaders of the anti-NATO forces, and has used his money and influence to launch attacks the coalition-backed government.
Although the Afghani proxy war was wildly successful in entangling the Soviets in a war of attrition, it destabilized Afghani civil society. The country has been wracked by internal conflict pretty much since the Soviet withdrawal, and it can be argued that the resources made available to Islamist insurgents by the CIA (through the ISI) was one of the major factors that allowed the Taliban to be successful in their takeover of the government.
If you're interested in Bin Ladin's trajectory, I'd recommend Lawrence Wright's The Looming Tower, which does a fantastic job detailing the origins of al-Qaida and the motivations behind 9/11.
If you're more specifically interested in the history of mujahideen groups and US involvement with them, I'd check out Seth Jones's In the Graveyard of Empires. Both books are quick and easy reads, and together, they provide a great look at the poorly-understood roots of the conflict in Afghanistan and US counter-terrorism efforts over the last few decades.