Also looking for advice on how to negotiate the current deposits that the owner should be holding for the current tenants.  

If that is the case you may REQUIRE your investing to match your current income. 

I own a company which matches renters with properties, and I keep a database that tells me exactly what people want, what they can afford, what location, etc..

Just a lesson to all of us that sometime the best answer is one we may not have heard of or thought of before.Could you explain a little more what made your house and this company a good match?

They likely will want a ROFR (right of first refusal) to match other offers. 

Same strategy works for buy and hold too ... my guys never have to ask me what color to paint a unit or never have to hunt for a color match.

. - I'll leave the CPAs to the CPA question, but one thing I should point out:In the future, and for the lurkers, keep all your invoices for those one-time repairs and see if you can get your CPA to put them on Line 19 "See Statement X" and itemize out the repair expenses line by line to match dollar for dollar what is on those invoices.

I have a lease-option buyer who put cash down, 3 year option, $63,500 pp after the deposit. 

I would like to see anyone who invested in other markets that can match your success  IE out of west coast   .. but then again you had the 100k and the credit to buy that kind of property.. most folks starting out just can't do pony up that kind of dough so they go searching for the next best thing which is less expensive cash flow.

I gave the potential buyer two options, either they eliminate the appraisal contingency on the offer or they have their earnest money deposit go hard (non-refundable) after 10 days in escrow.