Visas

Just show up.  Literally go to the country.  They charge you like $120 for a 10 year tourist visa as you arrive at the airport (in dollars please).  I wouldn't bother with anything else unless you know you are going to work for someone there.  IIRC correctly there is a 3 month tourist limit, then you take the Buquebus ferry to Uruguay for a night, and re enter the country for another three months.  I am totally serious.  Same works in uruguay.  Some people do this for YEARS on end and never get any other kind of visa.  No visa needed for Uruguay either.

So what takes you down there anyway?

Things are getting 'messy' there again.  Your dollars are worth a LOT (do not do official exchange rate, sell them in stores and everyone will take them and pay you more).  There is VERY high inflation now, and it will get worse.  They literally blow up the economy there every 10-15 years and it is on the way right now.

If you go, definitely live in a good area (I recomment Recoletta though there are others), only change US dollars as needed (or use a US credit card as much as possible), and don't buy any real estate or make any permanent plans for any time soon.

BA is a totally fabulous city!  I LOVE being there.  Lots of great history, cheap public transit, generally safe during the day in the good neighborhoods, nice shopping, great steaks, etc.  Personally I would live there in a heartbeat, but I would never invest a cent there until the government gets its act together, which at this point may be never.