Is Spanish fluency required?
Fluency is not required, however, at least 4 semesters of Spanish is recommended. You can get by if only being a tourist, but interacting with Spanish Companies is much more difficult without a good knowledge of the language. Also, some of the host families don't speak English.
What kind of things will i be doing at my job?
It is different for each job. Because it is a PR trip, you will most likely be doing a PR related job...news releases, tv, radio, newspapers, magazines, PR firms. if you are not interested in PR and are just on this trip for the credit or experience, then they can do their best to fix you up with something you are more interested in.