1. you can prevent waxing the sides where the tacky tape will come by applying a strip of "painters" tape on the flanges prior applying release agent. when you will apply the tacky tape you can remove these and apply your tacky tape.
Or you wax the entire mould and have a quick pass with the mould cleaner from easy composites or acetone to remove some of the wax or any other release agent you've used.
2. best temperatures would be ambient temperatures of around 25°C and have your resin at the same temperature. You can go higher but will have to make a good estimate of potlife vs infusion time. The higher you go in temperature the faster it will infuse but the faster as well your pot of epoxy will start to cure
I would call this a matter of experience and trial and error
3. You can do it without gelcoat. But you will need a certain amount of fabric on the mould side to avoid print through. a good postcure while still in the mould will avoid printtrough of the core as well.
4. pressure is in my case always full vacuum. this is a matter of preference i guess. but keep in mind that when you open the resin inlet. Your vacuum will allready drop a bit so have the full pressure best to start with.
Hope this helps you out a bit, maybe other people will have a different opinion and that perfectly fine... I don't think there is exact science here in the composites industry. It's like every chef in a good restaurant having it's own way of making things and as long as the result is the same and people like it. it doesn't matter how they got to the result
Matthieu Libeert
Founder MAT2 Composites X Sports
website: www.mat2composites.com