I’d just get onto the Mach website and ask for a few peoples advise, there are a few Super 7 conversions and they’ll be able to advise on suitable stepper motors etc.
As for software Mach is good and very reasonably priced.
It’s all a steep learning curve though so don’t be supprised at making the odd mistake.
Seem to remember an article in MEW recently were a 7 had been CNC’d
Steve