roofing

Just wrapping up assembling the Walthers Cornerstone Roof Details. I’ve realized that I don’t know the exact prototypical placement of the various types of vents in the kit. Can anybody provide any insight/tips? The kit comes with everything pictured below:

Talking with a friend last night and he was struggling with paper shingles, he just didn't like "the look" once he was finished. Altho I've never done shingled roofing on the layout, I do have a building that uses rolled tarpaper. Most of us would use something more substantial in real life...