It just takes a bit of common sense when using the rotary,plenty of water and of course very gentle on edges/areas that look a bit dodgy.
I've never used a paint thickness gauge myself but anything that helps is a good thing.
Best machine IMO for starting or for the money is the Clarke one from machinemart,about £80.
Swap the standard 14mm threaded heads for the stick on Velcro faracela types,get a compound and polishing head(from any paint supplies,they'll know what you mean).
Their soft start,so instantly burning through is unlikely.
I burnt mine out after about 7 years of heavy abuse and that included 18 months being used everyday in my bodyshop,it was repaireable but I needed one that day so bought the expensive one that Clarke do which is ok,very well made but as a starter machine I think it would be a bit hard to use as it's only 2 speed and no softstart.