I suppose with a little bit of handywork one could replace the floppy drive with an internal hard drive in an LC. However, you'd be out a floppy drive...and an LC is not an iMac; floppies are crucial on the machine.

I believe, at least in the original LC, a bracket can fit in either side. They designed the left side so it could use an internal floppy drive (a few low-end LCs actually sold with dual floppies just like low-end SEs did) and I'd imagine both sides are identical as far as what brackets they could take.

Find the lowest powered drives possible. I'm not sure if they're the lowest, but I seem to recall the Quantum ProDrive LPS not taking a whole lot of power. Considering the ProDrive LPS was a common stock drive in the LC I'd imagine it doesn't eat up a whole lot of power (unlike those big hulkering drives in the Mac II series).