I think you're probably a bit more concerned than you need to be.
Your front wheel isn't going to turn too much on a trainer unless you're deliberately turning it. Mine just sits on the floor and I don't have any issue. Whether you need/want a riser or not will depend on the type of trainer you have (does it raise the rear wheel/part of the bike at all).
For sweat, I have something like this:
https://www.modernbike.com/kurt-kinetic-sweat-guard plus a towel over my handle bars. But, even that is likely more than you need. DC Rainmaker has said he has never used any sort of towel or sweat guard and he rides indoors quite regularly. You definitely want fans and stuff to keep cool as you're not moving, so there's much less wind to cool you down indoors. Wind causes your sweat to evaporate which cools you down. Riding with no fans etc. will make it much easier to overheat.
Lots of people ride out of the saddle regularly. While I'd be a bit wary of doing an all out sprint where you're torquing the bike a lot, some out of the saddle riding is almost certainly fine.