Suraj 2062...

As per my knowledge:

*You would continue to have F2 status as long as your principal maintains valid F1 status. You don't really have control over your current status if you are an F2.

*You can apply for TPS regardless of ur immigration status but if you really want to continue ur F2 status you can continue that parallel with the TPS status as well. Applying for TPS status does not revoke ur original status. Looking into the history TPS normally keeps getting extended so not applying for this could be the stupidest decision in ur life time.

*Scenario 1: Lets say you continue to have both F2 and TPS status. At the end of TPS status you should not have any problem at all to apply for change of status to F1 because it's normally pretty easy to change F2 type status to F1 since F2 status intent is not to immigrate to the states.

* Scenario 2: Lets say both of you guys applied for TPS got TPS and the principal F1 holder decides to drop out and give up F1 status then it gets little tricky. After the TPS period if you apply for change of status you may have to go thru consular processing. That means you may have to go back and get a F1 Visa. But again thats a big "May" so you never know.

Final advice: TPS is a great great benefit. You can get social security , EAD and stuff and you may very well know how important those two things are in the states. Also TPS normally keeps getting extended for a long time so don't waste a minute. Apply for TPS ASAP.