I have a great product, but how do you pitch an investor to park their money and potentially lock it for a set period of time.I know rents and appraisal values will increase in time, but I can not account for that when speaking with investors.

I think it would put me in a bind for an extended period until I can save more or raise additional capital for #3 (which I have not done at all as an investor).

Here's the really powerful end game - If you stay in that duplex for at least two years of the 5 year period immediately prior to selling it you will get to take the first $250K of profit ($500K if married) from the primary residence side tax free. 

We are scouting to target a specific niche market that would require furnished month-to-month rentals.Does anyone have experience with a la carte services for periodic cleanings, restocking, and maintenance?

You do not buy properties for tax consideration, period.

Generally, if you have lived in the place for 2 years of any 5 year period you don't pay capital gains on the first $250k if single or $500k if married filing jointly. 

we're looking at a property and the agent sent us an "exclusive buyer agency agreement" that forces us to work exclusively with her for the period of one year. 

I called around and no one can pull a title report in such a short time period.

The verbiage definitely makes it sound like they have the right to inspect (and will periodically), but that may go back to prioritizing "problematic" rentals vs blanket inspections everywhere.

My understanding is that you could be held liable for any lead poisoning for a period of time EVEN AFTER you sell it.