Biting

Ive always had a pet dog all my life, but this is probably the first time that I am taking care of a BIG dog that is actually sleeping in my room. Its a St Bernard and I got it when it was a little less than 2 months old and is now roughly 4 months and has grown 5x since i got it. When it gets so excited seeing me when I get home from work, it jumps up on me and sometimes has a tendency to bite. It stops though once I give him his toy. But he also bites some things around the room, though he already has learned to not bite some of the things like my computer wires. How can I further train him?

He also sleeps on my bed, and insists on sleeping on my side, hahaha, and when I drag him or place his toy on his side of the bed, he'll get the toy stay on his side then go on top of me or sit on my tummy while chewing on his toy, is he just wanting to be playful? Its just sometimes irritating after coming home from work exhausted and I rather sleep. So, would like to be able to train him to just play with all his toys when I am too tired to play with him. Any siggestions?