You can not assign an obligation to lend or finance, that is unique to that proposed borrower.

The old.....do I save on taxes and shoot down my ability to borrow....question.

They have to order an appraisal, pre-lim etc and the borrower must submit a complete package.

You can use your self directed 401k to make loans to other businesses via promissory notes at any interest rate you can set with the borrower.

While both of these could occur in conjunction with being over-leveraged, neither on its own is sufficient to conclude the borrower is over-leveraged.

Iif you are starting out and have little to no funds, I'd go with borrowing as much as you can for as long as you can.If you are an intermediate investor has good cash flow generating, you may want to mix it up with some 30 yr amorts, and some 15 yr amorts.If you are a seasoned investor, maybe not acquiring as many new properties, looking to ratchet down a little, then maybe go all 15s. 

And the 'rules' are spelled out so the mortgage brokers can qualify borrowers.

The financing contingency is the most common. it carries a lot of protection for a buyer and lenders not only protect themselves but the borrower too.

Interest/ misc costs to borrow money to fix will be $2,500.  

Interest/ misc costs to borrow money to fix will be $2,500.