Do we take the assessed value of the building, divide that by the total square footage, and then multiply by the square footage of one unit?

Multiply this by 12 to calculate your mortgage payment on an annual basis and you'll get the $425,616 number that is on the spreadsheet.The levered net cashflow is the NOI - Mortgage Payment.

I usually take whatever there income is and multiply it by 25% and that is what they roughly can afford.

I'm aware of how to calculate the normal property tax by multiplying the millage rate assigned to the property by the SEV, but is there a technique to estimate how much exactly the property taxes will increase after purchasing, or is it more of an estimate?

This is a model all GC's know and use from our material suppliers, we get a multiplier based upon our volume for our discounting from retail.

It's hard to find them, but I've found a neighborhood that'll multiply by 2-3x.How do I find investors?

Multiply that percentage-number with the cost to replace the item.3. 

You need people who DO know what to do with that $, not the other way around, we have $ beating down our door night and day, seriously, there is an avalanche of $ out there, so check you ego would be some good advice. 

Easy rooms like bedroom and living spaces I estimate $1000.I typically double the cost when accounting for a GC or multiply by .5 for a handyman.

I took the square footage of the target properties and multiplied it times the comps to give an "estimated sale value".