I guess it all depends on if you're going to catch the bug or not. If you get into SW
fever like most of us do, and especially it its the reef strain.... well you should start big. I don't remember how much light the torch need, but for most corals you need more than the basic FW
lighting. Also with a smaller tank you'll need to be very careful about your parameters, making sure you do weekly water changes for a tank that size, and daily top offs with RO
water. I don't see any issue with the hermit crabs, I've never had any issues with them. As far as tank equipment, to be basic with a tank that size, dry sand, live rock, heater, powerhead. The live rock will act as your filter, and the rock and sand will hold your beneficial bacteria.
OH, and lighting, others will have to chime in about that, and that also depends if you just want a torch or other corals too...