James:---You can install the vents that will be required for your yet to be installed plumbing. You should have a pretty good what will be best for you. Some folks prefer to have all penetrations for venting at the rear side of the roof (not visable from the front). If you have a crawl space above your new construction, the venting can be offset there. Provide a grade on the vent pipe of 1/4" per foot if possible so that any and all condensation or rain water will freely flow to the sanitary sewer.
Sizing of vent terminals varies from state to state....in Florida, each building must have one 3" vent through the roof. In areas where the snow flies I beleive a 4" is required because of frost closure...Lots of luck with your project..Bud