I'm wondering how common it is to play a plethora of instruments and by play I mean practice on relatively often. I started on upright bass and the moved on to bass guitar, guitar, piano, ocarina and then drums in that order. Also are there any professional musicians on this sight?

I was that way when I was younger. Started Clarinet, then alto and bari sax, bass guitar, guitar. What I stick to now is banjo and mandolin. Just remember to practice! It's so easy to let the music get away from you. Don't let it!