I believe that thread locker is a must on all of the set/grub screws, I just did a 12 hour print and all the screws on my y axis loosened as well as on my x axis, I even had one fall out. So thread lock will be your friend.
Unless you use RED, thread lock is only useful metal to metal. I don't think it will do anything plastic to metal. At least I do not think it will.
Yup, that's what I used, what weird and confusing is that mine is in a red container... But it is Blue
Dont let the blue lock tight touch acrylic parts or any color it will find any imperfection in holes and expand cracking them. If it was me i would use CA glue in such a small amounts it will work the same.
Now that I did not know, I got a little bit on the frame but wipe it off as best I could, luckily no cracking happened
I work on industrial stuff for the big 4 and if you drill a hole then use lock tight it might take a day but the holes explode. I have never used laser cut holes so it might be fine.