I have someone who wants to buy a rental house of mine with owner financing, we haven't defined details yet, but it is $36K over 7.5 years. what should the interest rate be nowadays??

Pick a few and dig deeper into those portions of real estate.Second tip: once you pick a niche to focus on (or while you pick one), define your short and long-term goals.

It's could probably be defined as a "B" or "B+" condo in an "A-" area close to the capitol of Denmark, so it would always be easily rentable.

You can even setup "Define Fields" where you personally program QuickBooks to give you a blank field to enter whatever data you fill is important to have on them or remember.Your chart of accounts, allows you to create sub-accounts, therefore, Owners, Investors, can be entered as "Sub Investors" etc., and when you need to pay them their percentage, just choose their names.  

As Kathy Henley said LLC can define partner roles if you have them.

In the long run we're all dead, so expand the time horizon enough and nothing is sustainable as far as any of us are directly concerned ... short of that, I agree that you need to carefully define your time horizon and assess the impacts that has on your strategy before you answer these questions ... or sometimes not even short of that; personally, some of my assets will go to my children, so my time horizon for some investments extend well beyond my own death.

But the markets I follow still have very low inventory compared to demand, and my understanding is that the Hyper Supply phase has two defining characteristics: New construction (which is happening) and increasing vacancy rates (they haven't yet broken their downward trend). 

Here is some good language on this from calcpa.org.When a self-employed individual maintains more than one trade or business, the questionarises as to whether the limit is based on the sum of earned income or loss from all trades orbusinesses under common control [as defined in IRC 414( c)) as modified by IRC 415(h)], or ifonly the trade or business maintaining the plan being tested is used.For purposes of the IRC 415limit, earned income for the self-employed individual is based on the sum of the earned incomefrom all the controlled trades or businesses, regardless of whether the related employer maintainsa qualified plan [Reg. 1.415-2(d)(6)].EXAMPLE: Andy, a sole proprietor, operates a law practice as a sole proprietorand has $100,000 of self-employment income from such practice for 2008 (prior tothe reduction for one-half of self-employment tax).

@Joel OwensTo me buying at a discount is that you have negotiated the price down from list, which sounds like you define that as buying at the right price.

@Kenny DemThere are myriad options out there, but you've got to define the type of loan you want.