Do we need a formal entity? 

There should be a formal dispute process for the appraisal, the lender should be able to help you with this.

Does anyone know or can point me in the right direction for the answer as to what I can charge someone after the rent is late and if there is a formal way of charging them that late fee?

I thought it might be helpful for this person (and perhaps some others) to commit to writing a formal personal investment philosophy. 

The broker said it would be "important" for me to formally counter and put the revised terms in writing. 

You will probably not be able to do a loan assumption, at least not formally, as almost no loans have assumability features anymore.  

Something you'd expect to find at an upscale ski lodge out west or in Aspen. 2500-3000 sqft, 4 bedrooms and a formal dining area.

Unsolicited advice…If I could do it over again I would have simply gotten paid to work in restaurants rather than spend $$$ on the formal culinary education.

@Savanna Collins- good questions  -to figure qualifying income  - lenders will use a 24 month  average of your  self employement  income off  tax returns  and  they will use the  Schd  E  income for  rental income  calculations  ...if  rentals owned  less than  1 yr  -  lease  agreement  might be  usable to  calculate the  qualifying incomes ...best  step  will be to  get a free  pre approval started  in order to  see what your  formal  documentation allows  .....also by  doing this  you will become  familiar with the  process  plus  be able to  find out what  your  shortcomings  might  be 

It may be a private individual or a friend but you want to ensure you have a formal contract that gets into the various details typical with a rehab loan.