If I should expand existing shed into main floor of home and just add basement underneath Shed, also advice on negotiations on price and so forth.

It's possible you may have to replace the LVP after 5-10 years if the cracking underneath becomes more problematic, but it's still probably a better option than reconstructing the entire floor.

If sewer is not available, how difficult is it to have sewer ran from the nearest treatment plant, or how difficult is it to install a package plant or what are the soil conditions which leads to what types of septic systems are allowed.6.

Just be sure you have ventilation underneath so you don’t get rot.

HVAC person, of course you will need to check the regular stuff, like soil, roof, lead etc.  

One of my properties, that's well rented out, has a crawlspace and the whole building is slowly falling apart; it looks really good, but the living room floor is sinking fast due to water and mold underneath; the plumbing is also cast iron.

Most are slab and due to our soil, we can get settling from clay expansion/contraction and also we get sinkholes in this area so when there are structural issues, it’s a must to get an engineering report to determine if they are caused by the clay or sinkhole activity.

With the steep elevation on often rocky soil up there, septic permitting and construction can be a beast.

.- an up-to-date parcel that is only land, but which has been over-assessed as having a house on it.Due to what appears to be an assessor's error from years ago that one can say "switched" the parcels, I think the taxpayer believes she has been paying taxes on the parcel with the house, and is unaware of the error.Questions:1)  Someone in the Tax Assessor's office in downtown Birmingham told me today that if I buy a tax deed for a parcel that has a house on it, but is only assessed as land, the tax deed only entitles me to the land underneath the house. 

Using an underlayment underneath the flooring will also keep the tenants in the floor below happy as it quiets footstep noise.