First, typically in this kind of deal you're offer units rather than percentages.

It seems like a good deal percentage wise, but the rents are low.

If you need to use the rental income to qualify for the refinance then you would want to rent before you can refinance so you can show the lease in place.PMI can generally be removed when the LTV drops below 80% on the first mortgage. lenders will remove it automatically when you drop below a certain percentage but you may be able to request it to be removed sooner with certain verification.

Is their a standard,or close to,percentage rate related to closing costs?

They will loan you a percentage of the total cost or appraised value after the project is complete, whichever is less.

Not to mention the foreign immigrants who flock to Silicon Valley and pump, geez, billions more into our economy.As to the rest of your points: percentages absolutely matter.

You'll need to move out of the property to create a deductible loss.Your deductible percentage - when you're sharing common areas is based on the percentage of square footage that is solely rented (you have no rights to enter unless you are performing a landlord duty) vs the total percentage. 

I figured my partner and I could pay someone a percentage of the profit.

They all vary in the percentage of commission they take as well.

With that said, the percentage of tenants I would trust to paint is small.