Advocate can be use on pregnant or lactating cats with supervision of a Vet. Please consult your veterinarian before use this product (or any other medication) on your pregnant or lactating cat.

Advantage Multi treats and controls common intestinal parasites: roundworms, hookworms and whipworms

Yes it is safe to use them in conjunction.

Yes, this cogent compound defends your favorite feline from the parasitic menaces of: Fleas Ear Mites Heartworms Gastrointestinal worms

It comes in liquid form.