-A higher pitch roof has a higher cost and should be considered if your duplex will be infill into an area where there are other homes with the roof pitch, but failing that we have not found that it has a real impact on appraisal (we are in an area of lower pitched homes however so take this with a grain of salt depending on your market) and a lower pitch roof means lower maintenance and capex costs.

Seems like there's a big range depending on who you ask. 

It also depends on loans that you are trying to qualify for depending on credit, experience, and other factors.

Really depends on the route you are taking as to market I'd suggest.

Depending on whether you use a "light-doc" program or a "full-doc" program, rates will change.

Really depends on what you are looking to do / what markets.

For a 3 unit building with one unit as a commercial space/retail space I would use either a 7 or 10% vacancy factor and perhaps higher depending on the viability/business strength of the restaurant.

Depends on the square footage of the house to begin with.

Michael,With regard to insuring the condo units, the amount of building coverage you should have on your policy depends on what parts of the building you own. 

This way, you can have passive income coming in from multiple properties regardless of where you are living at the time.Ultimately, the best strategy for you will depend on your long-term goals, risk tolerance, and level of involvement you want in managing the properties.