You need to establish this as your company standard.  

Or to start out with a 4-plex with a standard mortgage, and possibly live in one of the units for a year or so?

We have our standards and integrity's.

If you want to keep the tenant, I'd screen them like you would any other applicant before you close; if they don't pass your standards, have the current owner end their lease before you buy.

the cost went from a standard 10k fix, to 20k, killing the deal after we bought it.  

I replaced a 40 gal recently (this month)with new venting at about 25% of your cost (heater, venting, and labor) using a licensed plumber (not my handyman) but I have no idea what the cost difference between standard size single unit heater and the size you are referring to. 

I'm curious if anyone can walk through the calculations on IRR and CoC when an annualized pref rate is part of the deal.On a standard deal is the CoC usually the annualized pref amount so it's counted as just cash flow and not a return on capital? 

Once a Value is established you then evaluate the condition of the property to estimate the amount of Rehabilitation work required to bring it up to Market standards.  

Typically it will be 25% down and the standard loan paperwork (W2's, tax returns, etc) PLUS financials on the property (seller's Sch E).  

Standard yellow letters or are you looking for something more unique?