Not sure where to start with this...
I'm assuming Desert Hot Springs is in CA based on your location?
If the other 5 units are renting at $460 a month, why do you believe the current owner will pay you $700 a month?
As for HUD, it's not for the faint of heart from what I have read. No experience to advise you on requirements though.
Why put down $100k cash on a $135k property? Worse, why finance $35k with him at 11%? With 25% down on a commercial loan I'm guessing you'd be in about the 6's on a full term amortization loan. Is your credit shot? You're getting a terrible deal in terms of financing.
That said, at $135k... if you can achieve $3,000 a month, you got a great deal unless the property taxes are an absolute killer.
For rent... figure 50% in expenses (including insurance, property tax, and property management).
@ 3,000/mo * 50% = $1,500/mo * 12 mo/yr = $18,000 NOI
From that, subtract your "mortgage payment" to get your cash flow for the year.
Divide your cash flow by your investment ($100k) to get your Cash on Cash return.
To me, that's one of the most important numbers to optimize as I am looking to maximize the return on my resources. Yours could have been better with stronger financing terms but should be just fine going this way... $18,000 - $3,850 = $14,150 => 14.2% cash on cash return... better than the stock market but worse than most RE investors are striving for.