On the Inca:
If the Spanish are stalled or get their asses handed by the Incans early on, then I see it as likely that the Spanish crown puts a halt on military adventures aimed at the Inca and starts trying to trade with them. As information diffuses back to Europe about a faraway land that has abundant gold, I imagine some countries are going to try and send trade missions, which would quickly result in trade between the Inca and whatever European power(my bet's Portugal) exchanging gold for useful resources such as steel and horses. This trade could potentially be profitable enough that Europeans begin to see the Inca much like India and settle restocking stations in OTL southern Brazil and Argentina or alternatively, the Inca sail downriver and establish themselves at Buenos Aires which quickly booms into one of the most important cities in the Incan Empire. Thanks to it's trade with Europe, the Incan armies are more than capable of dealing with any potential Spanish expeditions and has seen a large diffusion of crops and animals, as well as hosting individual Europeans, primarily missionaries, who seek either wealth or to their gospel resulting in an even greater spread of European technologies to the Inca state.
The Inca, seeking further trade with Europe as well as to continue their traditions of mummy worship by securing more riches crush the Mapuche, secure the land surrounding the Rio de La Plata, and begin tentative expeditions down the Amazon river over the course of the Early Modern Period, as well as try their hand at seeking out the wealth of China that they've learned about from European traders, resulting in their establishing small outposts in New Zealand and Australia, as well as a major trading post in the East Indies in Java/the Moluccas/insert important spice island here. With access to abundant natural resources and a thirst for technological advancement, the Inca are poised to develop into a powerful player as the industrial era rolls on.
Pretty sure I've written something along these lines before. So whatever that TL's version of Buenos Aires is, plus Cuzco.