863211 please: H1b or F1

I am still a Ph.D. Candidate student, my I-20 expires in about 2-3 yrs.  I just started working full time a couple of months ago, so I got my H1b now.  If I were to go back to China, should I use my H1b visa?  What about my I-20 and F1 visa?  How possibly can I use it in the future?  Do i need to contact the international office in my school for a new copy of I-20?

Thanks!