I haven't seen much variation in the 2,3,4 range as far as vacant vs occupied.That being said I've seen a lot of 5+ unit buildings that are vacant.

While the cap rate is only useful if you're dealing with an income producing property at it's fullest or with achievable upside, the price psf can help you understand the variations according to size, location, and condition.4) To renovate or not to renovate?

There is some variation amongst providers.

As a long time local government official responsible for processing and making staff recommendations on this type of zoning variation requests, here are some recommendations that should improve your chances in achieving your desired end goal:1.

I've also see very large variation in bids with the highest being more than double the lowest.

Adjustments can then be made for slight variations like 3 bedroom vs 4 bedroom...As a side note, there are some buyer search parameter considerations.

One valuable lesson I've learned through out my negotiations so far is that I can expect anyone/everyone involved to attempt some variation of this, but that it's not productive to get angry at them for it. 

(Variations of this are probably the most discussed/recommended here at BP).

If that's your goal, short term variations in value don't make a lot of difference.  

The BRRRR Calculator does not have the flexibility to account for all the variations that are possible.Do you have Private Money ready for investing?