Hey Jonesy -
You're welcome! Couchsurfing and backpacking sound like a nice combination. I wouldn't think of "backpacking" like you would in the states - camping out, walking on trails, etc. You can probably do some of this, but you would need to be aware of a lot of things that I don't know, and can't tell you about. But it is worth checking into.
re Spanish - I would invest in a good basic Spanish book and spend some time brushing up (after graduation, of course). Also a phrase book and a small dictionary (perhaps even an electronic one, as these are interesting and can invite discussions w/ locals). A book I like is (something like) "Learn Spanish in 24 Hours." After a while in-country, you will likely pick up enough to get around ok. And if you start w/ someplace like Puerto Viejo, there will be people used to visitors who do not know much Spanish. After that, knowing Spanish will help your budget immensely, since hosts at the cheaper places to stay will know only a little English (if any). Also, you will need enough words to use the buses.
re: gems - certainly ask your new couchsurfing buddies about more, but to start with... Most of the places you will have heard of are "famous" and touristy because they are gems, so I would budget money and time for visiting these places. Where you stay is and how you eat will be the budget-busters. So, plan on staying in hostels and backpacker places (or homestays if you can - more on those later). When you stay in one place, ask the people there (guests and hosts) about places in the next destination. Hostels are usually difficult to find out about otherwise. Do not miss:
- La Fortuna (hot springs and viewing Arenal volcano). We stayed at Roca Negra Inn (http://www.rocanegrainn.com/eng/) (nice, not resort-expensive, but not backpacker-cheap either; recent visit was $35 for single)
- San Jose (capital city, museums, people-watching, UCR, "cul-chah," center for buses to anywhere). A lot of people will say "skip SJ" or "spend as little time as necessary here." Well, that's their loss - I live here, and love it! I can recommend Casa Yoses Hostel (http://www.casayoses.com/) a bunk in a dorm is something like $15 or $20, and includes a very basic breakfast.
- While in SJ, take a bus for a day trip to the Poás volcano. Likewise, visit Cartago, Heredia, and Alajuela (nearby cities that are capitals of their provinces.
- Orosi (small town / valley, hot springs, horses, Spanish school, homestays, lake, rugged park). A lot of travellers spend time here - you can spend about $6/day on a homestay if you go through the school (montanalinda.com); spend a week or three on Spanish lessons while enjoying the surrounding area. Or you can stay at the hostel, or ask about staying longer-term (ask about the place rented out by Doña Alis).
For all of the above, you can see my blog for more info and impressions.
- Puerto Viejo (!) (that's PV de Talamanca) I haven't written much about it on my blog, but you can read a *lot* on Lisa's 2 blogs: http://weathercostarica.blogspot.com/ and http://www.travelexperiencecostarica.com/
A nice place to stay is Cabinas Casa Verde (http://www.cabinascasaverde.com/), but a cheaper alternative ($5/night if you use your tent, a bit more for other options) is Hotel Puerto Viejo. A good site for the area is http://www.puertoviejosatellite.com/ - search it for info on the hotel.
Other places (you need to get info elsewhere tho):
- Rio Celeste / Rincon de la Vieja (volcano, blue river, north)
- Manuel Antonio (national park beach, Pacific - definitely ask about hostels to stay in here)
- Puerto Viejo de Sarapiquí (rafting)
- Osa peninsula (Pacific, south)
- Santa Rosa (Pacific beach park, north)
- Cerro Chirripó (highest mountain)
- San Vito (south)
Things that people don't think about bringing, but should:
- 1 pair light-weight long pants (need these for central valley - banks, theaters, etc)
- windbreaker
- layers (if you spend most of your time at beaches, but want to visit mountains, then you can put on several shirts and windbreaker, instead of bringing a jacket)
good luck!
Julie