The use of cash is in effect "buying" cash flow at a extremely high cost.

Be prepared.Seriously though, timing the market is extremely difficult.

I know I could have my accountant do this but it is extremely expensive for the 11 properties that I currently have.

Yes, it is - it may not show you OPTIMUM performance b/c you're building reviews, figuring out the nuance of that particular unit, solving problems etc. but a year should absolutely give you an idea of if a unit will perform.Question 3 - what is "good" NOI - that's extremely variant on location/rental type.  

Under this situation, my personal decision would be to pay down the private loans as aggressively possible (after putting 3-6 months expenses in a savings account as an emergency fund). the federal loans would be getting the lowest possible payments, and the longest payback period. 5% is nothing, and you can invest to get a higher spread as soon as the private ones are paid back. that being said, keeping the student loans increases risk slightly while investing. if you are extremely risk averse you should pay them off first as well. on the other hand, if you are a huge risk taker, you can invest your money now and try to make more than 9% return.

They either qualify or not; just like everyone else-it would be extremely rare that a sec 8 tenant would meet the same requirements as our regular tenants.

My extremely unqualified advice is to not pay that unless you have some sort of inside info on the property or significant experience in this game.

I think its still a great deal that is extremely low for a 200K+ house. 3. 

This is extremely helpful.

There are guidelines on how paperwork that corresponds to the specific investment should be filled out.I hope I didn't muddy your thinking with my answers but I will tell you the Solo 401k provider AND Fidelity have been extremely helpful and prompt in clarifying and of our questions throughout the entire process.