The magazine follower pushes up on the slide release when the mag is empty. When it's loaded it will release like it does when there's no mag in the gun.
Once you 'get it', stripping and re-assembling the Mark II isn't that bad. There are videos on Youtube and other resources.
I never let the slide drop unless it's loading a round. It may be hard on the bolt.
Before I had to switch to bifocals I was shooting some nice little groups, under 3" at 25 yards most of the time, sometimes more, sometimes under 2". Once at 75 yards I shot a 5 shot, 5-1/2" group using CCI Mini Mags. Now my eyes are really struggling and I'm thinking of putting a mini red dot sight on my Mark II.