An investor who has participated in a subject to transaction without lender approval should NOT assume that they are safe from note being accelerated because a certain amount of time has passed.  

I would assume any halfway intelligent human being would understand we mean "shut and lock" but maybe I assume too much. 

(Assuming it bothers you more than the vacancy and finding a new tenant that pays on time for 3 years. 

Worth the $5,400 yearly rent gap I assume ($450 X 12)?

In any contract you don't typically need a clause saying what you CAN do, its assumed you can do anything legally allowed as an owner including sell.

500k in capital gains would be amazing, but I assume that with that kind of profit the property would need to be in the upper echelons. 

If you want it confirmed - then yes, confirmed, assuming that we're talking about a property that will be held as a rental. 

In this manual (which I assume could be modified to provide to tenants) I include all the financing information (which you would not include for tenants) bank accounts, mortgage accounts, payment information, and mortgage payoff), a list of the contractors, what each contractor does, a list of upcoming planned or necessary repairs, and a copy of all leases associated with the property.

I like the location and the price is 650kFor mixed use properties as you describe (and I'd assume is located on SW 10th St.), I'd recommend that the residential units fully cash flow the loan as my experience is that mixed use properties are tougher to finance as most lenders tend to prefer one or the other and something in the middle gets more difficult.For example, and granted I don't know anything about the area/neighborhood, I would expect this property (https://www.realtor.com/realestateandhomes-detail/111-NW-Har...) to be easier to finance than the mixed-use property you mentioned. 

@Alecia Loveless is correct--tenants need access 24/7 to their electric service panel, water and heat, assuming those are individual utilities for each unit.