Hi All!

Longtime lurker here, decided you guys were the most informed on all things flying, so I thought I would give my questions a chance to be answered by the pros:

I'm going to flying YYZ-ORD-GRU-AEP in a few weeks, and was wondering about a couple things, mainly involving GRU.

I'm going to be taking the overnight flight from ORD-GRU (on UA) with arrival at around 09:00 and then making a connection to an AEP bound TAM flight at about 10:45. My question is as follows:

How does immigration work in Brasil? If I am flying in to GRU only to connect to another international flight, do I need to go through immigration and customs control?

Secondly, is UA & TAM international flights in the same terminal? Will 1:30 +/- be enough time to get my bags?

Thirdly, I've never booked a flight before with a third party, so I'm trying to figure out how baggage works: If I fly UA to ORD, UA to GRU, and TAM to AEP will I need to re-collect my bags everytime? Or only at GRU?

Lastly, If I miss my connection at GRU due to customs/immigration/late arrival on UA's end, will I be put on the next flight? Like I said, I'll be booking with a third party travel site since UA/TAM can't get the flights/rates I want.

Sorry for the long first post, and thanks everyone in advance fo the help!