If they see a flying insect, they will do somersaults high in the air trying to catch it. They also keep crawling insects at bay. In training, a simple strongly accentuated NO and a tap with a couple pages of newspaper will indicate to them that curtains and upholstered chairs are not meant for climbing and scratching. After a VERY brief time, just the sound of crumpling paper will be enough of a deterrent. They do not mind the dog at all, at least mine never did.
Fleas are usually more frequent during the warmer summer months.
For a bunch of fleas one would use a good flea dip, followed by the usual flea collar to control and eliminate the infestation. I personally have never had to give them a flea collar. They do move and elongate themselves somewhat. Your vet would prescribe either some pills, which may not be as easy for your to administer as it appears when the vet does it, or a shot. A follow-up in about a week does the job.