My Dog Constantly Rolls On Her Back And Wants Her Belly Rubbed.?

I recently got a 2 year old Papillon mix. My friend adopted her for my birthday knowing i had been ready for and wanting a dog. however when ever you walk up to her or play with her she rolls on er back and just lays there. this gets in the way of training her to learn to stay and sit when all she does is roll on her back and waits for her tummy to be rubbed. now i don’t know if this means anything but this dog was left in an abandoned house when her last family left her lock in a house. she was only found when someone called to complain of a barking dog. She had several rotted teeth and had many pulled and the remaining where deep cleaned. they told my friend she was most likely abused due to how extremely hand shy she is. Now however she is glued to my hip and never leaves me. i was wondering if her rolling on her back could be what she did when she was hit like playing dead? is there anyway i can stop this act?

What Is The Best Way To Train My 3 Year Old Papillon To Stop Barking Constantly?

My Papillon is a 3 year old male and he barks at EVERYTHING! Guests coming to the door, other animals outside, other people/animals walking down our street, he looks out the windows in the living room and barks when there’s nothing there! He barks when we come home, when we leave! He barks at the SLIGHTEST little sounds! What can I do to limit him to barking once or twice or not at all when NOT NEEDED? He also jumps on everyone who comes in the door! HELP! Please, no suggestions that would harm or be considered cruel to any animal!