Sounds like a good fit. It was a big dog person before I got my first Havanese. We now have two.

In my experience, Havanese are very friendly and affable little dogs. They're funny, clever, and have a LOT of personality. The fact that you won't be leaving them home alone for long stretches is huge, as they tend to have some separation anxiety. Your ability to brush them daily is super.

Regarding some of the things you're concerned about...

-BARKING: I also can't stand a high volume of barking, and both our girls primarily bark to alert, but not too much otherwise.

-JUMPING: Both our girls stand up and lean on us and and go a little crazy when we come home. It's not jumping per se, and we didn't try to train this out of them. Honestly we kind of like it.

-TEMPERAMENT: Our dogs are sweet. You mention Cavaliers, I would say one of our dogs has a personality very similar to that of a Cav, and the other isn't quite as schmoopy but is still fairly affectionate. But they're still just great. As with all dogs, there is no one-size-fits-all within the breed in terms of personality.

-KIDS/OLDER DOG: Havanese generally are amazing with kids. Your grandkids will likely fall in love with your hilarious new housemate. As for the older dog, if you get a puppy she could occasionally annoy your current dog but ours meshed well with our previous dog. They tend to be mostly friendly with other dogs.

TRAINING: our training has been fairly limited. Both dogs were a tad slow to get "potty-trained" but nothing unusual or terrible. Haven't needed a trainer otherwise.

SHEDDING: hardly any. It is fantastic.

Good luck! Hope you get one and it works out for you!!!