The tax code says very little about the type of assets that can be invested in within a tax-sheltered retirement account.So, from the perspective of the congress and the IRS, mutual funds and real estate are equally OK for tax-favored retirement accounts.For a variety of reasons -some good ones and some not-so-good -  standard IRAs, 401(k)s, & other QRPs impose "artificial" restrictions on the assets that the account can be invested, thereby restricting you to the provided "menu" of investment choices.However, although congress and the IRS don't have much to say about what type of assets your 401k/IRA/QRP - they do care about "self-dealing" with those accounts and have put in place rules to prevent that."

Can I do 1031 exchange to avoid paying taxes on 100k or just the 25k Your 1031 needs to be on a property that is greater than or equal to your selling price and debt. 

Assuming the services are provided adequately and equally, which model provides the best value to me?

Their record doesn't care that they are living life straight, it sticks with them, so finding other housing is TOUGH which equals low complaints and low turnover for you.What you need to look out for is a pattern of recent bad decisions.

All rents being equal, is there any benefit to turning the 4-plex into a duplex?

This is why I charge a deposit equal to 1.5x the rent.

Default provisions may be designed by state law, but many times, providing a deed-in-lieu-of-foreclosure (quit claim deed) held in escrow to be filed after thirty consecutive days of default in payment can be something that makes it more attractive to a seller and can be a trade-off for a lower rate or less in the down payment.And, in the pre-payment realm, having a penalty equal to the tax liability (especially in the even of default) can be an issue.

The deal is for electricity.It seems like everything I read about NPV referes to equal installment annuities.

Having the secondary exit strategy is crucial and you may use that to weigh in on your decision to purchase one property over another (ease of retail exit to owner occupant buyer)

So here is how your deal looks:$600 gross rents, less $300 expenses, less $175 HOA expenses equals $225 left over for debt service and cash flow.Lets assume you pay only 93% of list price, your purchase is $28k.