Barbara, there is a procedure in the manual for adjusting that port if your edges aren’t square to the sides. It’s in the back in the FAQ section. You loosen this screw on the right:
Then move this lever: to adjust the height of the right side which is what controls your angle relative to the guide fence. IME, this needs to be adjusted on every new machine but rarely needs to be readjusted.
I would take something with a square edge that you can scratch up and stick it in the port just until it makes contact with the wheel. If it hits on the left side only, raise the right side. If it hits on the right side only, lower the right side. Rinse and repeat until it makes contact along the full edge. It’ll take some tweeking but it’s not difficult.
I suspect that will solve all your problems with the cutting edge squareness. Flattening the backs takes some practice. Lay it down using the edge as a fulcrum so the cutting edge makes contact last. Put your fingers on the top of the chisel to keep it flat and make light contact. No pressing down, just enough to keep it in place and flat. When it starts to feel a little warm, pivot it back up raising the cutting edge first. Cool and repeat until it’s evenly removing material. The keys are laying it down so the edge touches last and picking it up so the edge leaves first and letting the abrasives do the work. If you try to apply pressure, it will roll to the side or try to run away. Also try to point the edge along the rotation like this: and not to the center like this: If you do the latter, the wheel will try to roll the left side of the chisel under. With the former, you aren’t fighting against the chisel rolling.
Good luck! You’ll have the hang of it shortly. Work up some beaters until you do then get out the good tools.
For bevel angles, I like 30-35 degrees for bench chisels and I do all my plane blades at 25 degrees. YMMV. When it comes to sharpening, opinions are like farts. Everybody shares them but nobody likes anyone elses as much as their own😉
