Check out the wall street journal article today which reports appraisers being asked for tighter comps in the neighborhood, six months reserves and "permit" information on remodeling.

Can I invest it all and have a zero balance, or will I need to keep a certain amount in reserve?

That is why you have depreciation and reserves to deal with these repairs when it comes due.

I still get aggravated where the government lets the tribe buy a piece of ground off the reservation, then place it in trust and become exempt from taxes. 

So, you're wondering why your brother, that's basically a hard money lender, is having reservations about working with two partners that have zero skin in the game?

At this point, I only have enough money for a 10% down payment and a little reserves, so I'm going to attempt to get a 60% non-recourse loan, and see if the seller will finance the last 30%.  

You also want to decrease that risk if the gas or electric is off, heat, cold, sump pump issues, etc.Utilities always want 48-72 hours but there are also always reserve or back up schedules you can get on if you push enough.

If I could find a way to start back today,I would have no cash reserves.

Hang in there and find the "right" tenant.In the future, when you find a replacement, start building a reserve account of money so you will not have this pressing issue on you and you can afford to wait for the right tenant.  

Once you go over that mark (5 - 10) your allowable LTV's decrease on new purchases, your reserve requirements go up and your risk is higher so your new interest rates will reflect that.The best interest rate is going to be on your primary.