don't try to bath the cats without elbow length leather gauntlets & full protective clothing, unless they are used to being bathed
may we ask how old the cats are ?

if you really think it's neccesary, let some poor professional groomer or vet do it, rofl, we would not advise bathing the cats, they often become ill after bathing unless you have experience in restoring the protective oils to the fur
(sorry to sound like such a know-it-all, but we breed cats, & when we were younger we bred dogs)

there are herbs you can plant in the garden to discourage fleas, & the puppy can be given garlic pills, these will really help, he may even be happy to eat fresh garlic, the cats will not unless they are old, but if you provide the right herbs the cats will roll in them & this helps too.

Suitable herbs for this would depend on your local climate.