Looking at a duplex for 65k only is tied to the owners house, which has an existing mortgage, however the house isn't part of the deal.

We did that on one we have and turned it from breakeven to a positive cash flow of around $1500/month - albeit we ended up with a bit more capital tied up, but our overall returns jumped significantly. 

I'm looking for some assumptions for my underwriting for the cashout refi on an industrial property with a credit tenant and 9+ years remaining on the lease after stabilization.I'm specifically curious about rates, amortization period, term, and LTV. 

MHs are a depreciating asset if they are not tied in with the land. 

The remaining portion you could do a 1031 exchange on to buy something else that may work better for you.Being able to sell something tax free needs some serious thought. 

All the and and ins and outs will cost as well (tie in, notary, endorsements, yadda yadda and a) - the escrow or attorney chosen can vary by thousands of dollars. 

I've been living in it since and renting out the two remaining rooms. 

Sounds like there are two living units on the parcel, but it's hard to understand through your question which structure(s) remain.

If there is $500 net after all expenses ex management fees, then he can take a $200 property management fee and you can split the remaining $300 50/50   He gets $350 and you get $150.  

Total Purchase Price $396k$164k loan still exists on property For remaining $242k, Seller would accept payments of $800 per month the first year, $900 per month second year, and $1000 per month after that until the total amount is realized.