Hey dude, your call name looks very familiar I think we've spoke before.
Anywho, the type of connector depends. Are you using Single Mode Fiber or Multi Mode Fiber? Most fiber is labeled. If it is a short distance more than likely it is going to be MMF.
Anyway, you don't need an SFP unless you just totally want to do fiber, you can uplink via copper if you have free space. With that said, if you choose to uplink via fiber, the type of fiber you are using is going to dictact the gbic you buy.
If you are using MMF and the run is less than 550m you'll want the MM-SX gbic, if its longer you[re probably looking at SMF and will want a LX adapter (normally long distances - 5K+).
If your linking to a core switch I would recommend etherchanneling for redundancy so it may be more cost effective to go the copper route if possible.
