I have three rental properties that add up to around $10K in property tax. THEN, I have my primary residence, which has $10K in property tax alone. Can I write off the rental property taxes off under "other taxes" on ...

Make sure to exclude t.

You can probably exclude him just because he requires someone else to pay his rent for him, doesn't qualify on the basis of income. 

Yes,  That tradeline/debt will be excluded once you show proof it has been paid. 

Area: Colorado Springs, CO (in a nicer part of Colorado Springs that draws a lot of tourists and outdoorsy individuals)Price: Asking was $550, we bid $555 to beat out another offerConcession: After a lot of back and forth, the concession we've received is 15K off for a total price of $540Cash Flow: Excluding the major repairs, property will cash flow around $100/month (including property management) before the additonal unit and closer to $700 per month after the additional unit, conservatively.Loan Terms: 25% down, 3.5% rate 30 year loanThe CAP rate at the new price ($540K) is 5.8%, which is in line with other buildings in the area (Avg is around 6).

I've recently encountered an interesting scenario that I hadn't considered before.All following numbers are approximations and exclude any tax implications:I've recently purchased a property for $90k.

This is not something you exclude because you know the borrower and have a 15-year relationship, any more than you’d exclude fire insurance because you know one another.

Under IRS Section 121 - if you live in your primary residence for 2 out of the last 5 years you can exclude up to $250K of capital gains as a single taxpayer. 

@Holly BarrettSection 121 exclusion($250,000 or $500,000 exclusion for living and owning a house for 2 out of last 5 years) will always(99% of the time) be better if available over a 1031 exchange.Section 121 exclusion excludes the gain meaning you never have to worry about paying the tax while 1031 exchange just defers the tax(potentially forever).I would say maybe the only instance a 1031 may be better is if your house appreciated much much more than you are eligible to exclude. 

(excluding paying in cash) thanks.