Rosebud, you dont need to be "fluent" to communicate! What is fluency anyway? Its been debated among academics for years! I have been here 10 months, came with basically NO spanish but am now upper intermediate. Studied 15 hours a week for first 6 weeks, and was having basic conversations after that. Since I can now speak with my girlfriend and colleagues in spanish, my spanish has improved heaps and I am only taking 1.5 hrs of classes a week. And I can tell you, I dont think I have a talent for languages!
My point is, why not set learning Spanish try and take some before you come (even if not classes, there is plenty of audio and online courses avauilable) and when you get here continue taking classes. Once you can have a basic convo (which doesnt take that long) you can really improve. The Argentines are actually relatively patient IMO (younger generation particularly) with people tryign to speak the language. Especially if your keen to go out to the bars / boliches and really get involved socially, you may / may not find life long friends but I am sure you will find locals to hang out with.
You may not get to "fluency", but you will well and truly be able to communicate and your Spanish is likely to be better than most peoples english here! It will make your experience so much better overall.
A comment on the plastic surgery / superficiality, yes Argentines are superficial, but IMO no more than Aust, NZ, USA, Europe. But, they are more open about it here. The girls are very hygiene conscious and concerned with their appearance. But they are much more open, and likely to admit they are that way.