with an electric fuel pump you just need to run a fused power (12v) from the ignition preferably and ground it somewhere. i just grounded mine on the subframe like so. its mounted to a rubber exhaust mount - lines up perfectly with the holes. note i havent hooked up the power in this photo.
its pretty much all dependant on the size of the stereo you looking at putting in. 4 speakers run off your head deck will be fine on the stock electrics. throw in splits a sub and amps, then you really should be looking at a quality battery and an uprated alternator. convertable mini is the man to talk to he has the uprated alternators and electronic kits for dizzys - do a search on electronic distributors on here, theres plenty of info about them