What is a Demand for Possession?

We also make sure the tenants understand the full security deposit stays with us until the unit is returned to our possession at the end of tenancy.  

If a lessee of real property remains in possession thereofafter the expiration of the hiring, and the lessor accepts rent fromhim, the parties are presumed to have renewed the hiring on the sameterms and for the same time, not exceeding one month when the rent ispayable monthly, nor in any case one year.It appears as you stated that without specific language to clarify the issue, once the intial lease term expires, the lease has to go to a month to month term.

To do this, I'll need to syndicate the deal, which meals I'll need to possess a track record of success in (I'm assuming) smaller deals.

For the tax liens, that is more of a long term commitment as the state you choose to invest in will very possibly have different laws and time frames as to when you buy the lien and when the lien is either satisfied or you are able to take possession, which is not an easy process. 

@Jane Dang  Here's a notice template for you (it's the one I use in California):60-DAY NOTICE TO TERMINATE MONTH-TO-MONTH TENANCY TO: (tenants' names),AND ALL OTHERS IN POSSESSION of the premises located at: (address of rental property).YOU ARE HEREBY NOTIFIED that effective SIXTY (60) DAYS from the date of service on you of this notice, the periodic tenancy by which you hold possession of the premises is terminated, at which time you are required to vacate and surrender possession of the premises.

Had I possessed the knowledge I have now, I wouldn't have wasted 10 years waiting. 

She can buy the note on the house but she won't be listing the house for sale without taking possession of the property through foreclosure or some other means (deed in lieu, etc).

The typical use of land contracts is to protect the interest of the seller (make it easy and cheap to regain possession of the property in the event of non-payment) with a less than stellar buyer.

But make sure you give the proper notice for September.Take possession, get it sold, chalk it up to a life experience.