The kill switch is easy enough to fit - it all depends on the pickguard and the space available in the cavity. Important to note - you have to play with the gain really cranked up to get a clean machine gun attack. It's just my opinion, but I think that playing with low gain sounds bloody awful. I fit a killswitch a month or so ago for a customer and it was coupled with an in phase/off/ out of phase wiring configuration on each pickup. I hated the killswitch effect, but the young guy loved it. I guess I'm just old school!
Converting to a split humbucker - I would start by replacing one of the 500k tone pots with a 500k push pull control knob. These push pull knobs sit a LOT deeper in the control cavity so I would recommend that you measure the cavity carefully to see if it will fit before you start !!
You cant really go wrong with trying different wiring configs. There are a lot of tutorials and guides available for everything on the web. You just need a ton of patience. I'm currently wiring up a Brian May configuration that feeds from the selector switch into the volume pot and then feeds into an onboard preamp and treble booster. Fortunately, the preamp came mainly pre-wired so it shouldn't be too hard......famous last words eh?
Good luck !!