If you and the tenant can work things out amicably and determine a move out date + monetary amount for early lease termination I'd also speak with them about having permission to show the unit prior to their move out date. 

Find out the date of the "switch" and make a new listing and block calendar until that date. 

And also,When I draft the contract for the seller to sign, how far out should I set the closing date on the contract?

Trust me, you've seen these templates all over the internet.

For example she starts dating a carpenter or a handyman type (or even worse a wannabe carpenter or handyman) who moves in and does work on the home and claims they should have equity too for making those improvements.

How about internet?

Anyone reading this thread should make it a point to read your state's real estate contract practice book or at minimum pull a list of all C.A.R. forms from the internet and read the title of each form and pick a few to read line by line to begin understanding the contract language. 

Once you have them served and file the papers with the court, the court will assign a First Tier Hearing - basically a mediation session where hopefully you are able to work out a move out date certain (with the tenant paying use and occupancy).

NCREIF produced the first property level return index, the NCREIF Property Index (NPI), dating back to 1978 tocapture investment performance records that meet the rigorous scrutiny and review of major investors and academia.What is the NFI-ODCE?

At a bare bones minimum, the letter confirms the start/end dates of the lease, monthly rent, paid-through date, absence of any prepaid rent other than the current month, and security deposit amount.Better, it will include statements there are no unresolved claims or disputes or repair issues with the current landlord, and no verbal or written side agreements.Better yet, it will include a copy of the tenant's lease, and a confirmation the lease is a true and correct copy with no amendments.