"Commercial penetration went hand in hand with conversion, conquest and the founding of new cities." - Phillipe Dollinger, The German Hansa

I think I'll be able to answer your first question. As for the second question, it seems more like a subset of the first question. I'll talk about the initial Christianization of Livonia, specifically Bishop Meinhard, so that you'll see how relationship between crusaders and merchants go back further.

Focusing specifically on Livonia, we begin with the arrival of Bishop Meinhard in the 1180s near the Gulf of Riga. He subsequently founded a church in Uxkull in 1187, which became the headquarters of the Christian mission in Livonia until the founding of Riga in 1201 by Bishop Albert von Buxhovenden. We know from Henry's Chronicle that did not arrive in Livonia alone, he came along with a number of German merchants, who were experienced with the region:

German merchants, bound together through familiarity with the Livonians, were accustomed to go to Livonia, frequently sailing up the Dvina River. (Henry of Livonia, 2-3)

Being knowledgeable of the region, these merchants must understood the risks involved, yet, what prompted them to accompany Meinhard? As you may know already, the only major port closest to Livonia was Visby in Gotland; merchants from Visby (who were either Swedish or North German) would then go on up the Baltic Sea, into the Gulf of Finland, transfer their merchandise onto a smaller ship and sail along the river Neva to reach Novgorod. This journey was both hard and restricted as once winter came, the sea and rivers would freeze; the trade route was open for roughly six months (give or take). Therefore, it was natural that merchants would investigate the possibility of a land route, which might not lead them directly to Novgorod, but could allow them to trade with the Russians that inhabited the regions north of the Daugava River.

Knowing that a land route could be viable, what made the merchants support or accompany Meinhard? Safety for their merchandise is the most obvious reason. In both Henry's Chronicle and the Livonian Rhymed Chronicle, the pagans were viewed as different - not German, with different values. Including their tendency to go on raids and take what they wanted, it is implied that the pagans in Livonia did not have a legal traditions: either relying on a supernatural entity or on themselves. For the merchants, this was a huge concern; part of the reason why they would have support a conversion was to implement German - Christian laws (Peace of God) and the notion "that property was somehow inviolable and that merchants merited a sort of protected status (Munzinger, 116)." Furthermore, trading with the pagans was dangerous for Germans because they would have been treated as outsiders - the pagans in Livonia saw the supremacy of kinship. Merchants could do nothing if they injured or wronged during a transaction. By implementing Christian law, the merchants saw this a leveling the play field, both to secure themselves and their merchandise.

While I didn't explicitly touch on the relationship between the Hansa and the Baltic Crusades, the interactions of the early Christian mission in Livonia would have seen support from the Visby and North German merchants as a way of insuring their goods and expanding their trade areas.

Primary Sources:

Livonian Chronicle of Henry - by James A Brundage

Livonian Rhymed Chronicle - by Jerry C. Smith

Secondary Sources:

Forward To The Past - A Cultural History of the Baltic People - by Endre Bojtar

The German Hansa - by Phillippe Dollinger

The Profits of the Cross: Merchant Involvement in the Baltic Crusade (c. 1180-1230) - by Mark Munzinger (I drew heavily from this article, which I think will answer a lot of the questions you'll have regarding the relationship between merchants and crusaders)

The Baltic Crusade - by William Urban