My dad and step-mom have 3 dogs (2 pugs, 1 australian shephard mix) and 1 cat. The cat pretty much ignores the dogs and stays out of their way, but the dogs do the same to the cat. They aren't friends, but the co-exist perfectly fine.
Growing up, my family had a cat and a labrador retriever. They would sleep on the same bed together
We have a 5 month old labrador retriever that we've had since he was 2 months old. We also have 2 cats. The cats are fine with the dog most of the time, but there are definitely moments where they would just rather the dog leave forever. The puppy tries to play with them and doesn't understand that they are hissing at him because they hate him. He never touches them and wouldn't hurt them I don't think (and is never around them unsupervised), but they aren't buddy buddy. They are getting better and I think that eventually they will just ignore each other.
There are so many breed-specific rescue groups that you should be able to find the right dog for you. Pugs are cute, but I would also look into shih tzus and lhasa apsos and other smaller-sized dogs. On http://www.petfinder.com
, you can search by size and/or breed. If you type in 'pug', it will bring up pugs and pug mixes.