I get to subtract a dollar or two each time I make a payment - woohoo - so it would take me 194 regular payments to get to that "fair", evenly divided $592/month interest portion.

Calculate the NOI by multiplying the number of spaces by the lot rent, and then multiply by 12 months, subtract the expenses (can range from 30-50%, that % depending on the variables above). 

In all cases you're losing money...just in different forms.1 - Speculation is not investing...unless you have a buyer already lined up.2 - Basic math:  You start out $20k in the hole  (DP), then you get equity (virtual money, not real money until you access it) at $6k/year...so it will take you over 3 years to break even...but not really since you're started out $20k out of pocket...and have negative cash flow every month adding (or subtracting) to it.3 - So, you're happy with 100% equity...from funds out of pocket.  

If we take you mothers place with $1700 per month rent and subtract 50% for expenses (average on a SFH) you have $850/month after expenses.

There is no rental income on the property only the return on the equity.Now subtract the expenses at say 50% which is roughly $1250/month therefor 0 - $1250 = ($1250)Ball park this property is roughly $1250 per month negative cash flow.

Something about them subtracting the cost of the utilities from the voucher value.It makes me angry that as of two years ago, Cook County forces landlords in Cook County to accept tenant applications from section 8 applicants, and then don't lay out how it works in an understandable way on their website.

Subtract that from their income and see if they can still afford your rent.Also, related to "free search on the county's website", that's a good resource for that one county only.  

All four are responsible for the rent, so I assume the easiest way is to just subtract one and add the other. 

They will flag any major problems to subtract from value.

Can the owner subtract the lost rent for those 15 days from the deposit?