I think you have a new member to your household. Potty training isn't that hard & the chewing faze can be handled by providing so good chew toys, bones(raw only), antler, sticks, wooden blocks. If you puppy proof your home, there won't be much destruction. Just by putting things up & not leaving them down where a pup could get to them, it, or what ever. Creating a safe enviornment for the pup.
Consider using an exercise pen for dogs instead of a crate. Keeps puppy safe while your are gone.
There could be something wrong with the pup if it was just dumped. I'd take it to a Vet for a wellness check up & get it started on its puppy shots & dewormed.
Get some puppy chow for the pup, if it has teeth it can eat the hard kibbles. If not soften the puppy chow so the pup can chew or eat it.
I have always had two of what ever animal I have had in the past. They can be each others companion. You don't have to worry about them not getting along.