I'll throw in...
I have a 1997 Z3 1.9L. Owned since new, now in its 29th year of service. 201,000+ miles. Not being able to drive your car, so no way for me to tell if what shift issues you are describing are normal or not, but most folks new to BMWs do find the manual transmissions shift a bit less smoothly than a Japanese brand vehicle.
The Z3's Getrag is no different. It has a short shift kit from the factory and is notchy in 1st and 2nd gear. Most everyone finds the 1-to-2 shift at low speeds/low RPM disconcerting, especially on a cold transmission. Nothing to worry about. But if you have concerns, try driving another Z3 to compare it to, or take it to a BMW indy shop for their evaluation.
BMW uses very stout driveline components, especially in the legacy cars of the Z3's era. Just keep it and drive it. Best way to get out of the seat is swing your legs out first, use your right elbow on the A-pillar and lift with your legs.
Try to not get the BMW OCD disease.
