Hey Skinn... - over 200 views and no replies ? ? Not very helpful, so I thought I'd give some thoughts. First, your title doesn't say you have questions so most views are looking for info themselves. Maybe put in some Q-marks ?? Second, I have the standard B22-FV (NOT SR), not the Precision but much of the action is the same.
The Q's about manuals you'll have to search for, unless someone else chimes in.
Q-3 about the cocking pin - the vids by Miles Sun ( http s://www.youtube.com/watch?v=I1dzc9dYhw0 ) is what I believe you're talking about. Follow his advice, he's right. His vid is over 2 yrs old, back when they came out with B22s - others are copycats.
For Q-4 - I've only shot about 5-600 rounds - of many diff brands - so I don't know about wear, but it makes sense that when that occurs, you could 'sharpen' the tips of the extractors. I saw a vid about that on YT, so someone's had the prob.
Q-5 re the mags - my best advice is to insert them with the bolt open. I do occasionally have them 'hang up' and completely 'seat' if I don't. I haven't had any problem with 'not picking up a round'. ONE prob that I've had - that is noted on YT vids - is fired cases jamming in the receiver, BUT that's from 1) Not cycling the bolt with authority and 2) empties occasionally hitting the scope and bouncing back down and hanging up there. Both NOT 'real problems' of the gun just the operator ;-)
Q-6 - As for the bolt channels, if it bothers you you could smooth them a bit. I would use a Very Fine File, then hit the edges with 400 w/d (or Finer) paper to polish. You should do this to the cocking pin above, too. I did polish where the bolt handle locks down in the receiver, as that corner was pretty sharp on my rifle. Just like on the cocking pin. Best to reduce wear wherever you can. YMMV
Good luck and I hope someone with a Precision answers you, too. Try a YT search for "Savage B22 mods" for lots more stuff.
Ed