Short answers:
no, only to a certain degree, no, it should be a rotary vane pump.

Long answers:
-higher capacity is nice to have, but you could absolutely infuse a full size yacht with a 5m^3/h pump. It just reduces the pull down time of bigger moulds.
-single stage, oil bathed rotary vane pumps have always (at least i never saw an counter example) have a final pressure low enough for every composite task. There are better ones, but lower final pressure doesn't really get you any benefits. 99.95% vacuum is the pressure you are looking for.
-if you are not dealing with ridiculous large or leaky mould/vacuum systems the continuous working range doesn't matter at all. You are not working at 0,5 bar, and if you are you should use a vacuum reduction unit, so the pump still is under full vacuum. If the bag is massively leaking, every pump will get damaged after time.
-oil bathed vacuum pumps are the way to go. In terms of durability, final pressure and nominal capacity there is no better system on the market. For the heavy users an oil circulation pump, like the dvp pumps ec is selling is an upgrade to think about. But for hobbyists oil bath rotary vane. It is as simple as that.