How to get rid of fleas and gnats(fruit flies)?

Hi, we have a bad case of fruit flies because we had bananas out and we forgot about them. So I cleaned all the counters and table and the stove. What else can I do to get rid of these fruit flies? Also, we have a bad case of fleas as well due to the fact that we took a cat in from the streets last year and we also have a cat already. He had some last year as well but we got rid of all of them. Or at least we thought we did, but this year he has them again and has given them to our other cat. They are all over the house now biting me and my girlfriend now as well. When we go to the bedroom, living room, or kitchen they jump on our legs. Is there any way to get rid of these things as fast as possible without hurting our cats?