In regards to tightening the lock screws and then having the hammer rubbing/hanging up on the wood stock. Wood behaves in a predictable manner depending on the amount of moisture that exists in the atmosphere. Often if kept indoors, the wood dries out, contracts and gets brittle. Conversely, in a damp environment we all know it does the opposite and it swells/expands.
The most common cause of what you describe however, is the tendency for people to way over-tighten the lock screws and draw the metal insert washers on the opposite side into and compress the wood. Musket lock screws just need to snug and not torqued on. They serve no structural purpose other than to hold the lock in place.
If you intend to shoot the musket, you want the hammer to strike the nipple in the middle of the hammer recess and not skewed way off to the side. Just go to a hardware store and find some thin flat washers that will drop into those inserts. Snug up the lock and see how it lands on the nipple.
Odds are, that the barrel is a "smoothbore" at this point but can still be fun to shoot. There are people that can reline that bore for you if you desire to make it a real shooter. The gun is old, so keep your powder charges down to 40-50 grains of FFF black powder. You can shoot a patched round ball out of it which is cheaper than shooting musket bullets.
Also, if you don't know a lot about guns, take it to someone who does. It is not uncommon to find these wall hangers are still loaded, so treat it accordingly.