Argentina to Johannesburg - Layover Question

[TripleRazor]

Hi all. Not wanting to drive to Brazil to avoid the Tourist Visa application, I plan to fly from Argentina to Johannesburg, Africa with my bike. However, all flights seem to layover in Sao Paulo, Brazil, change planes, and then to Africa.

Could you please help:
1) Do I still need a visa if I am just on a 2+ hr layover?
2) I read a lot about shipping the bike first. Do you mean on, say, an earlier flight? If yes, do they know to just keep the bike until I get there several hours later?
3) Is there any known issues with them having to switch the bike to a different plane, or is it handdled like luggage would, just moved without any input from me?

Look forward to any help. Did I mention I've never done this before, or did my questions give that away