I get sx gbics for around $120 through my company, shouldn't be too much more, you certainly don't want lx or zx, they'll fry the receivers with that short of distance. When you consider the cost of most switches that NEED them, they are dirt cheap. If you already have a giga switch there is no need to use the fiber unless you have long runs that exceed ethernet.
Single mode 3m patches are around $30 and multimode are $20 both for duplex cables. If you don't know if you have 65um or 50um, get 65 as it will work with both (multi-mode).
LC is a small connector with a tab you push down on top to release, sc or snap and click is a square connector with a sheeth that click into place, they are about 3 times the size of LC, and st or stick and twist, are round metal things kinda like a keyed bnc.
Aggregation of two gige ports is kinda useless for what you're running, a 2 gig backbone is a lot for most small business'! Almost all ethernet networks today are star, bus is a very poor topology for network resiliance.
I'd throw a traffic monitoring program on the switch and see what kind of traffic you have right now, unless you have a link saturated at 70% or more under load, you don't need to aggregate links.