Simple removal could cost $3500 but if there is leaking into the soil it could cost $10k-$20k easily is my understanding.Does this make this a potential seller financing deal? 

Let's make it simple...he wants $50,000 after his loan (mortgage) is paid off...That amount is $105,000...so he would have to sell the home for more than the combined amounts?  

But something as simple as asking for proof of income will be something you never forget to do again.

It is not as simple as saying everything is calculated per square foot.

Very simple.

If you're helping him out it's simple; get him in touch with a local Realtor who speaks his language.

Any recommendations for a web dev that can create a fast lead gen site with a simple UI that I can add content onto is appreciated.I would say finding a good realtor is probably my weakness at this point. 

This is the simple brutal truth of it. 

But to keep it simple, you need to sell or cash out refi.If your plan is to build a large rental portfolio, you're not going to sell that property for what...10 years..20 years? 

I think for a manager that keeps it simple and less time 'looking up' information when tenants call or e-mail.