Depending on the amount of work you will do, you may or may not need actual architectural drawings and engineering calculations if you are moving load walls. 

Welcome:)  If you have any questions on local land development, I work for the City of Surrey in Land Development Engineering.

@Michael Garofalo I am an Electrical Engineer, but not an electrician.

You really need an engineer to put together some site plans to see how many units you can fit with ingress and egress, setbacks, sidewalks, septic, traffic signals, etc.

I'll go back and review the details again and try to reverse engineer how he came up with those numbers.

When the two meet, you invest in that market...and the range you are looking for is established for you.However, with that in mind, here is what will dictate those numbers when you are coming from both sides...and reverse engineer your answer from both ends to the middle.1 - Rents in the market areas2 - T/I in those areas3 - Cost to buy in those areas4 - Cost to finance your buy (refi)5 - Cash flow left over after all expenses/month factored in6 - Min cash flow required based on your goalsExample here in Michigan (doing this deal right now):1100 sq ft 3/1.5 ranch w/bsmt & 2 car detached garage in Redford, MI$47,000              My cost to buy/rehab/etc...in cash$64,000              ARV (will be higher in spring/summer too)$48,000              75% ARV for refinancing in 6 months$  1,000              Cash out at refi (on top of cash back of $47k)$     950              Rent/month$     350              All expenses/month inc PM$     600              CF/month before REFI$     243              REFI PI/month$     336              CF/Month with REFI in place, and NO CASH left in deal (actually, I get                                  back $1,000 more than I started with)My criteria was:1 - All cash back by the time I refi, and 2 - At least $300/month in CF with the refi (and PM) in place The Market dictated:1 - $1000 Rent2 - $47,000 max. 

I had a structural engineer take a look yesterday and he wasn't overly concerned.  

Start with high-income professionals that you deal with on a regular basis -- doctors, lawyers, engineers, etc. 

I am 33 year old working as a software engineer with a mega corp here, have saved up some decent money and investing it in index funds.

I am a full time engineering student by week and full time employee at a manufacturing corporation by weekend.