None of the older Leica VF's lock, never used a new style.

Since most finders are designed for use at infinity I doubt there's any vertical compensation for composition. If you're not that precise with composition anyway, I doubt you are going to see any difference in any of them.

The older Leica type use a frame(sort of) internally but it's in the rear, at the eyepiece and it does have a correction line to deal with parallax at near distances. The framelines being at the eyepiece however don't allow you to see outside the lines. You're viewing directly through the front element.

I owned a CV finder at one time. Two things I remember, No lock, and it had been dropped and the frame was knocked out of horizontal alignment.
It was an obvious defect but an easy fix.(plastic crap). :o)