I don’t want to have to rely on local internet connectivity.

Tar leases are on the internet for an example of a good lease (but it is for Texas and copyrighted).

For example, internet.

Heat & ac, basic cable or internet packages, parking, storage etc.

don't know about that state but I know CA OR and WA have very strict laws on what you can and cannot do with someone in distress IE in foreclosure.. check with the state or a good real estate attorney taking advice from the internet is not wise with something like this I think .. unless an attorney familiar will pop on and give an opinion..

You have provided internet and it works properly.

Strangers on the internet, including BP, might be helpful, but your best bet is going to be folks you can meet face to face and show the deal.

Taking a generic contract off the internet scares me. 

This is a question for a lawyer not an internet forum, also you might want to make sure that the buyer is actually interested in the specific property you have before you sign the contract because if they aren't you could be stuck holding the bag.

I am living in a cave house (yes, we have electricity and Internet) in southern Spain.