like above the computer then restarts
and also missing some drivers: graphics (VGA)

I would like also to remove as much as possible, which things are not necessary?

Start by reading this and this. Try not to remove too much at once, but take it step by step so that you can isolate problems which might occur. If you still experience probles afterwards, please post what exactly you configured in nLite, which hotfixes you add, et cetera.