But it will depend on the specifics of the partnership and your relationship with the investor.

Zoning and codes have changed over the years, so depending on when the alteration was done it may be ok (but that's doubtful).

Depending on what your objective, your calculation will be different.

It all depends on the extent of the non US person's presence in the US.

I'd leave the floors but if you hate them just float a floor over them.other ceiling options would be tin tiles depending on size. or gluing wood inserts to the mirrors and paint those.

It all depends on the quality and type of soil you have 2 feet underground.  

it depends on your area, and what  you're looking to do?

Depends if it is a permanent partnership or a partnership per project.

You also need some business cards that have a couple things for you to write in manually like your phone number but not your cell phone number.Another thing you should consider, depending on your financial worthm, is to form some sort of corporation or a LLC,  Expect that most banks are against doing a loan that not in your name, even a transfer.  

Depending on how long they've been in the military, it's can be extremely difficult for that transition and finding housing is one of the most stressful events they will go through.