Basement bathroom - venting and check valve

[jvalerius]

I am putting a new bathroom in the basement of our 1938 home in Wisconsin (UDC applies, I think).
I am getting quotes from plumbers for the work and hearing different things regarding what we need, so I am looking for more opinions about a few things.

Background:
The location in the house is near where the waste line leaves the house, and it is not near the main vent stack.
We live on a hill and there is no history of sewer backups.
The kitchen (directly above) was recently remodeled and the vent was replaced with a mechanical vent.
An adjacent wetbar is mechanically vented.
The new bathroom sink will be mechanically vented.

Questions:
1) Do the shower and toilet each need to be vented, and can the three sink vents in this area serve that need somehow?
2) Is a check valve required? If so, where, relative to the new toilet and shower?

Thank you!

[jnaas2]

Unless you arent going to pull a permit call your building inspector and ask Him or Her what they will require and then have the plumbers give you a price so you can compare apples to apples. Some companys will low ball the price and not pull a permit and it wont be installed according to code, You need to know what is required according to your local inspector and your local codes.