There are LOTS of different shapes of chin rests. Go to Southwest Strings and look around. You probably should find people with violins and try diff. chin rests before you buy one.

The allen wrench thing is not actually to adjust the chin rest, but to take it off the violin, or tighten it up so it stays on better.

You might want to try a shoulder rest; there are several diff. kinds, I like Kun.

To stop slipping pegs, either buy Peg Dope or powder up some rosin and dust it on the pegs while the strings are loose, then re tune.

Even if you play by ear, go find MOTW at JC's Tune finder and try to figure out the bowings on the sheet music gif. A v means up bow, an inverted |_| means down. A ( over two notes means tie/slur and notes are in the same bow. When I do the B part of MOTW, I use 4th finger instead of an open string. On the A part, I use a first finger G string (a) for a double stop or tune the G string down to a low d for a drone.