This service is more widely available now and my rationale for having that element remains primarily to speed my ability to respond to opportunity since I go to a lot of auctions. 

The suggestion of transferring the property to an Corp sounds like it wouldn't help in this situation.A lender will not give the ability for an officer of a corporation where he/she has no profit interest to take capital for lending purposes.If there is no mortgage, your brother can consider doing a cash-out refinance.

For questions 2 and 3, You'll need to check the state where the property is located to determine.

The ability to rent will be there.

What are the best sites to determine what your property may rent for?

How do you figure out how much money you will pay in taxes at the end of the year on CF you made from your property. What is the percentage they use? I live in Illinois. 

I am concerned about this initial hit impacting my ability to qualify for a mortgage, or qualify for a better rate, and therefore wondering if I should pay off my loans ASAP to allow for recovery.

Not the ability to market, negotiate, analyze, take photos etc. 

Talk with your tax advisor to determine what the tax consequences are.

One must have a great acquisition strategy and the ability to execute on the upgrades.