If you park at a remote stand (or even somewhere that isn't in B terminal), you''ll be bussed to B. This is usually 1/2hr delay. There isn't usually much of a delay for passport control. depending on your departure gate, there can be quite a long hike (eg to the end of the A councourse). I wouldn't be booking the earlier flight unless you're prepared to standby on the later one when you misconnect.

Your luggage will be forwarded right through, so no need to worry about that.