Note that for 6 months, your best (and only, really) option is short-term furnished housing (otherwise you have to sign a 2 year contract), which there is an abundance of here in Buenos Aires. If you want to live alone, plan to spend between $500-$700 a month with everything included (utilities, phone, cable, internet, and usually weekly maid service).
Large, short-term rental option that doesn't charge commission is
Buenos Aires apartments for rent, Buenos Aires hotels, host families, travel Argentina they also have English speakers. If you want to spend less you need to find shared housing; use
Habitaciones en Alquiler & Departamentos en Alquiler. Craig's list is not a good place to look since it's all in gringo prices. Otherwise, I wrote an extensive housing post that is now in the articles section.
Palermo is definitely a nice neighborhood and I personally recommend it over Recoleta/Barrio Norte, which is lovely but not very accessible by metro (subte) and also overrun with international students (mostly US and British) who are here 'learning' Spanish; for me it's a tiresome crowd. I live in Congreso and love it; cheaper than Palermo, very central, and much safer than people give it credit for, not to be confused with nearby Once which isn't the greatest. Also, the microcentro is filled with offices and upscale hotels, and therefore crowded by day but abandoned at night and on weekends, so I don't recommend that area either.
Bring all the electronics you'll want and plan to power them using adaptors. I bought a small hair dryer here, it was the cheapest I could find at $35 US and it is made of a questionably safe material - nicer onces are closer to $60, just to give you one example. Otherwise, food, movies/theater, transportation, and clothes/accessories are all cheaper than in the U.S., though not exorbitantly so.
This particular website does not organize events, but Democrats Abroad and Expat Connection both do; however, if your mission in coming here is to learn the language, I recommend avoiding organized English-speaking affairs and throwing yourself headfirst into the culture - there are tons of free and cheap cultural events such as plays, concerts, musicals, dances, tango lessons, and so on. The more English you speak, the less Spanish you'll learn.
If you have other questions feel free to contact me privately. I too am a single female living in BsAs. Good luck with your preparations!