Bottom line: if you can't easily get the valve on and off it's too tight.
Bottom line: If you can remove the valve without tools, it's not torqued tight enough.
You can get a torque wrench and judge for yourself. 50-foot pounds is a bit tighter than what I can achieve by hand. Your experience may be different.
Yeah - TECHNICALLY - which is total bushwah and is solely for the enrichment of dive shops to do totally unnecessary, and trivial "work"
It's not a total bushwah, but a full VIP may not be required either, especially is you're filling with just air. As someone who fills cylinders, I am not going to take anyone's word that a cylinder is "safe."
If someone removed the valve of an air cylinder, and it otherwise had a current VIP, then I would just eyeball the inside of the cylinder and the valve threads before filling the cylinder again.
Removing the valve of a cylinder that's certified O2 clean invalidates the VIP sticker and requires re-cleaning and a new VIP. Period.
The reason that dive shops have "ridiculous" VIP requirement is because of all of the unethical lawyers and scuba divers who hire unnethical lawyers. If dive shops didn't have to worry about getting sued just because they used common sense and deviated slightly from "industry standards," then common sense would prevail.
Unfortunately, lawyers are greedy and unethical.