To clarify I am revising a lease from another source and it currently states 'no firearms are permitted' which I am changing, I was just curious on what others experience has been to be mindful about regarding it. 

You can Google stalk (sounds like you already did), search the property in the register of deeds for sketchy titles, see if they pulled permits (sounds like new construction prob wont work), check the mortgage info, and (best of all) hire a good inspector. 

Secondly, where serious efforts are required, tenants will not get permits and way down the road, you'll pay for that with inspection violations and delays in attempting to sell. 

(b) Conditional use conversion — authorized. (1) (i) In all districts except the R-2, R-4, R-5, and R-6, the Board may authorize, as a conditional use, the conversion of a building for use by more than 1 family, as long as the number of dwelling and efficiency units to be allowed conforms with the applicable principal-permitted-use bulk regulations for the district in which the building is located.

(value add)I recently began the permitting process which included updating the building a bit to bring all units to code and hiring a surveyor because no survey existed on file.

If it is over ten thousand, a permit is likely and hire an architect to supervise because he can place a stop work order.

This is to include any building permits or licensing requirements.

Some situations permit a simple act of filing a document and getting it approved by the court so that title can be transferred, which is called a summary probate in some jurisdictions.

I know you have to have permits as well.

I was very busy with other properties at the time, so I thought nothing of it and moved on.Fast forward a year: I'm combing through some permit records and I find that the subject property was purchased by the "well respected developer" and he was now building on the "un-developable" lot.