I have this sudden urge to respond whenever I see the name, Tulane. 🙂
First off, congrats on your interview invite! Tulane's a great school and I am practically a walking advertisement for them since September... As for the student host option - definitely take it! They'll fill you in on the general gist of the school the night before so you'll have enough info to ask intelligent questions to Dr. Pisano the next morning.
My host was fantastic - she even gave me her queen size bed to sleep in while she slept on the couch! They are, however, not required to pick you up from the aeropuerto. The ride from the airport is only 13 bucks (ridiculously cheap by Cali standards).
Good luck!!!