Its been awhile, but I don't remember having to mess with the screws to get the steering wheel off. I know I had to do that to remove the lock assembly, that sucked. Should be able to just loosen the wheel nut and remove. Can't answer the spline question though. Just try the fiero one out, you never know. But it probably won't fit.
Getting the wheel off is a pain though, I just had a flashback about that from when I installed my momo. Good luck