Hello,Tenant is on a month-to-month, written lease.I have informed tenant with appropriate notice that their lease is up at the end of the month. 

At this point, our decision has been to issue a Non-renewal of lease notice with the idea to renovate and flip it.

Remember to give written notice that the lease will not be automatically renewed (refer to the current lease agreement you have with the tenant).   

Did the inspector notice anything that would lead him to believe there is a problem with the sewer line- slow drainage from an appliance or toilet, or maybe a big tree near the line? 

Some states are very clear that the buyer can have access for specific essential inspection purposes (measuring for furniture not being essential) and others are wide open and allow the buyer access for anything with proper notice to the seller.

Tell them in a written notice, it is prohibited per their lease, it is dangerous and is cause for eviction.

You may find an unauthorized pet or notice damage.

 I am interested in a pre foreclosure property that has doc type "notice of dispendens".

If you look at 10-15 yrs then there might be a more noticeable spread.I wouldn't necessarily rule out PLG.

But after looking outside I noticed a security camera pointed toward the street and front of the house.