Bath Drain/Vent Review

If you have a second please comment on the isometric I drew for my basement bathroom layout. I just want to get a comfort level before I begin gluing this up. I have two additional questions maybe someone can help me with:
1. When I transition from the drain to the vent on the shower can I use a 2" "y" with the branch going to the shower?
2. Where the 2" drain line from the shower ties into the 3" toilet drain do I have to come in above the centerline of the pipe or is it OK for everything to be in the same horizontal plane?

Thanks,

David

Flat vent for the shower?

Yup, the vent for the shower would be on the same plane as the drain.

That is a problem.

The vent must be downstream of the trap and cannot be horizontal until it has risen at least 6" above the flood rim of the lavatory.