Quick recap
So far, I've defined my needs and that for some parameters, I don't actually need any form of user input to get the information required - this lessens the amount of time the user needs to pratt about and increases the amount of time they are enjoying my lovely social networking site.
Another parameter that I don't actually need to bother with is asking which country they are in. I can find that out a pile of different ways (such as looking at the IP address why they are entering data). Another method is to use geotagging.