Do you really need to remove all the exterior paint and window trimmings for the FHA loan, or would sealing it under new paint suffice?

Neil did a decent job outlining how it's done.Given circumstances, I'd simply get your brother to provide you something along the lines of a pre qualification letter.This should suffice the realtor.  

Will that suffice for CYA?

or will one suffice depending on what the property's used for?

A general range will suffice.

This need not be expensive, sometimes just doing a slightly better paint job, or a feature wall, or painting kitchen cabinets will suffice. 

For example, if you put in granite countertops and cheaper ones would have sufficed.

Suffice to say I have a lot of reading ahead of me, not a bad thing.

Even if lost in mail, your certied copy of recorded doc will suffice to resell.In His time, not yours.

Are you sure your insurance company has an issue with it being without tenant for a short remodel period and a normal rental policy with rent loss coverage won't suffice?