You should definitely not do any invasive skin procedures, including dermarolling for at least six months after the last Accutane dose.
If your scars did not respond to all the treatments you have had, such as twelve Fraxel sessions, it is not very probable that dermarolling will work too well on you.
As I explained here, lasers and dermarolling works on the same principle:
http://owndoc.com/dermarolling/how-dermarolling-works/With a 1 mm size dermaroller, you should roll every 10 -14 days.
It would have been better to purchase a 1.5 mm dermastamp instead of the 1 mm size because you seem to have very stubborn scars and in the future, if you get some results from the 1 mm size stamp, you could even consider a 2 mm dermastamp.
It is a good idea to try the suction pump, as none of the treatments you had were targeting scar tethering.
The skin does get dry and rough right after dermarolling because the skin is being deeply renewed and it takes some time for the protective film that prevents water evaporation from the skin to be reformed after dermarolling.
The instructions for single needling are in our dermaroling instructions:
http://dermaroller.owndoc.com/dermaroller-instructions.pdf