In my experience, when we acquire a property that has had a tenant for an extended period of time at below market rent, they will not want to pay your price. 

The small bank/credit union you bank with may be able to get you some solid deals if you’ve banked with them for an extended period of time.

The bank had mentioned extending the construction loan term if I wasn't 100% finished with the rehab, but I wonder if I should just bite the bullet, stick with them, and look to refi later?

That's why buyers dealing with wholesalers need to know the laws about Alabama redemption rights, which can extend after the tax deed has been issued. 

They have asked him to extend and want to charge a $20,000 extension fee.

Most lenders hold back the repair funds and they establish a timeline as to what needs to be done and release the funds as repairs as made. 

Get it in writing.3. can you use this modification as a reason to extend the lease for a non-standard install?

Despite what it is, it should at least be addressed. 2 months rent is pretty common with proper notices.Some states require you to make every effort to re-lease the property and some don't. ie, you could technically have the tenant pay the whole lease period even if you don't fill it.Regarding pets, we used to just not allow pets but based on our experience, almost every house that the owners had no pets somehow winds up with them.

A sacrificial rod that goes into the tank, it can extend the life of a tank for years (Search youtube: anode TOH) 3.

Today is the last day of an already-extended inspection period.