That's good news your getting a 3d printer, Deano and I can help you out if needed 👍 , maybe start with using petg as it's a bit trickier with settings than pla , the slicer will get it in the ballpark, then it's your job to adjust a few things here n there. You'll enjoy creating stuff in CAD and seeing it evolve into a real part.
Correct, SS isn't very strong so can't be used on any mild stress point. Those little kits are handy, mine is being used up on the heater box, grill etc , added to rivnuts has been a good combo !
Yerp, 8.8 or 10.8 grade is the go