Can any one advise me what esle megajolt can control ? ie rev limiter, fan switch etc or point me in the direction of a site with the full wiring information, I only appear to be able to find how to wire the EDIS 4 into it using the PIP and SAW wires

Autosport Labs should have all the info you need, there's a usefull forum on there too.

yes you can do a soft rev limit by retarding the ignition. alternativly you can do a hard rev cut by adding an extra board to the v3 and v4 models.

there is a car installation guide here
click

you can control the fan by using an aux input coupled to a temp sender.

I've got a version 4 manual, can send a copy if it's any help