If you visit the Vatican Museum you dont need to go to the Sistine Chapel, Right before you hit it you can turn around and go back. You are not forced to go in the Sistine Chapel.
There was supposedly a large jewish exhibit in the vatican museum, but I did not see it.
I had a Money Belt so there was no way I was going to get Pick Pocketed. You would have to tackle me to get it. I rode the subway there no problem. There were a few scammers in the train station so keep your eye out for your luggage (I took the train from Rome to Venice. Its 400 Miles and it took less than 4 hours)
Frankly just walking through Rome is Fascinating, there are many old things to look at, There is a lot of Archeological digs going on.
Italy is very proud of its jewish heritage unlike other European countries and they encourage you to visit the jewish sites (The Arch of Titus is considered by the Authorities to be a Jewish Site)