I think this is a good attitude. But don't be afraid to borrow tactics from YouTubers or other people on this forum. It can help when you're just new.
Mentality affects everything in your tactic. Broadly I like to think of it influencing risk taking and the speed of decision making. As you move up in mentality you are telling your players to be more direct, to press more often, to have a higher line of engagement, etc. There is nothing wrong with only creating tactics on Balanced. It's a good starting point and that way you know more clearly what the Team Instructions will be changing.
I'm not sure what the question is here. But I like to create space for my fullbacks a few ways: 1) just by having more players in the midfield than my opponent, 2) having a narrow attacking width which encourages outside to in passing from my wide players, and 3) focusing play through the middle which encourages my midfielders to stand closer together pulling defenders to the middle. But these are all functions of the tactic I play. So it might be useful to share your tactic.
You're on the right track. Look for traits like gets forward whenever possible and enters opposition box late. Also think about your tempo. If you're playing too fast then there isn't enough time for the midfielder to make that run into space. And finally don't be afraid to play your striker on attack.
You got the right idea. If you notice a bunch of ridiculous passing over the top you can untick it or hit play more disciplined or run at defense to make your players not pass into space as much.