The problem with the mouse-look mode in v1 viewers is that it is handled differently than in v2+ viewers.
In fact, the whole asynchronous pick/synchronous pick logic is different (e.g. the right click is an asynchronous pick event in v1 viewers, that is handled in a callback, while it is a synchronous pick in v2+ viewers), and if you try to implement the same tricks for mouse-look as found in some other v2+ TPVs, things simply do not work properly (e.g. you loose the "gun" mode, and/or the mouse cursor for the UI does not show and leaves you mouse-cursor-less, etc)...
I had a look, but so far, the only "clean" solution I can see would be to reimplement the object picking logic, which is not really a trivial task and would likely introduce many bugs (that would also impact the line segment intersection logic which is used in many places in the code for the cursor/world interaction and more) that then would need to be addressed...
I'm afraid I have no free time to spend on such "features", especially since I personally find no incentive in this: as a genuine role-player (i.e. my avatar bearing a different persona from mine, and therefore a different "point of view", quite literally), I pretty much never use mouse-look (i.e. first person view) and I even implemented a "Spoof mouse look" feature (CTRL ALT SHIFT M) in my viewer to evade scripts trying to force me (or you) to stay in mouse-look !...
As for #5, if it is indeed a bug, please use the
bug report forum and provide accurate repro steps.