Definitely check out inventory and DOM, this gives you an idea how fast or slow the market is and help estimate your holding time.Also pay special attention to other flips in the area.

(THESE ARE ALL ESTIMATES UNTIL I GET MAINTENANCE COST THAN I WILL GIVE NEW OFFER)Also take into consideration this is not so much a 5 plex conversion, it acutally seemed like an apartment building but just a very old one from the 1900s.

I estimate it would take 30-40 rental units to need to spend 750 hours a year managing them.  

I estimate my crew and I can fix it for (3k).

Scott The Book on Flipping Houses, The Book on Estimating ReHab Costs http://www.biggerpockets.com/flippingbookYou might consider Niche or Specialized Housing like student housing.

Do you know the exceedence interval that estimate is from (e.g. 100-Year Flood = 1% chance of water reaching that elevation in a given year)?  

Things like local renter density, vacancy rate, rent estimate, etc..  

Anyone here use Xactimate or similar to estimate rehab costs?

Scott The Book on Flipping Houses, The Book on Estimating ReHab Costs http://www.biggerpockets.com/flippingbookConsider checking out HUD homes for small multi's owner occupied gets first crack.

That always helps when estimating rehab jobs.