Michael, is that you? Ha. This is exact same story with us. Adopted a 2 year old lab. back in Nov.
Our solution: kennel train. She didn't go in the kennel. So we just kept her in there when we were away or couldn't keep strict watch over her.
Patience is the next best advice we can give. The moment you take her out of the kennel, take her for a walk and don't come back until she goes. At first, it's going to take a while. I remember one day I was getting especially annoyed -- 45 minutes! And she finally decided to go. :/
Our rule is: if she goes, she can free roam the house. Else, she goes right back into the kennel and we try again in 30 or so minutes.
Today, now 7 - 8 months later, she's allowed to free roam most of the time, but we still keep her kennel bound for feeding and bedtime (and in the car when traveling)
We still have pulling issues, and leash aggression. But we're working on those independently: prong collar while walking, slow introductions to other dogs. If we see a dog on a walk, we intentionally get ourselves between her and the other dog.
Crating will keep the mess off your floor.I would crate until trained. I would reccommend you take her/him out often and give them treats WHEN they go outside. It would be no different getting a dog who has been tied outside all their lives. Leading depends on the dog.. what we were trained to do is
long lione and teach them the following one areas for poddy. you should walk them. leading is done outside or inside. a long 5' line that have several break hold( knots ) to catch if it slipps. treat and rewards when they reach these goals. sit , down stay come are important. classes reccomended.
Treats she showed us were hotdogs cut in very small sections and baked til crisp.