i think people are just trying to give you a realistic view point. that said, i think it totally awesome that at 16 you are already thinking this way! i'm a senior in college right now, and i started learning spanish in 5th grade, and have continued all through college with a spanish linguistics major. i have lived and studied in both Granada and Bilbao, and those experiences have probably been the most influential in my life!!! I only wish I had been thinking that way at 16! So good for you.
that said, what you are talking about doing would be really tough, not to say it cant be done! like i said, i started learning the language in 5th grade, from native speakers, and now consider myself to have near native fluency. when i studied abroad i took all my classes with spaniards. even though i didnt really struggle much with the language, there is a LOT more that becomes involved. it took a lot of getting used to the different style of classes there, different way of testing, grading, and just a really different university environment in general. i guess what im trying to say is that its a lot more than just speaking the language
i eventually learned to love it all and would do it again in a heartbeat.
However, as much as I love Spain, Id even love to live there some day!! I cant say that I would have wanted to do my entire degree there. You are asking us to compare it to a US university, you cant really do that. At least at the two universities i studied at, even UoG, which has over 50,000 students, there really isnt that residential, campus "college" feel that you associate or get at big US universities. Its just different, most students, at least in my experience are living at home with their parents, and are from the surrounding area. Its a very different atmosphere than where i go to school in the US, with lots of students living on a campus, a campus town, residence halls and student apartments, sports teams and lots of parties and school spirit
I would have felt like i missed out on the whole "college experience"
Anyways, im not saying dont do it, im just saying really think about it. there are lots of other ways to get the chance to live in Spain! You could spend a year abroad, intern abroad, there are so many ways. I do remember that there is a translation program at the UofG I believe, although i cant remember which facultad it was in right now. you can search their webpage though:
www.ugr.es Good Luck!
Kelly