Do I need to reapply Advantix after bathing my dog

Recently, we moved into a house that had fleas in the back yard. We had no idea until we took our dog out after moving in. Our legs AND our dog were covered! We tried dusting the yard and used Diatomaceous Earth in the house, and on our dog. The fleas didn't die off. A few days ago, we got K9 Advantix II, (purchased from a pet store) using the lesser dose pkg for his weight since he was right at 55 lbs. After supper, we put the drops on our dog. The next morning we let him out to use the bathroom, he walked right back onto the porch and collapsed, then went into a seizure. We took him to the vet right away. They did everything they could, even kept him overnight. He died the next morning at the Vet's, before we even had a chance to be there for him! They said it had gotten into his system and there was nothing more they could do. The Vet said this shouldn't be sold over the counter, that Vets can test for a reaction in a safe environment.

Waterproof Formula K9 Advantix II is waterproof, so there's no need to reapply after your dog has a bath or goes for a swim

Protect your dog from fleas and ticks with anti-itch relief spray and flea & tick medicated shampoo. Purchase the K9 Advantix II Solution*, and a PetStylist will apply it after your dog's bath or groom.

Can I bathe my dog before or after applying K9 Advantix

Waterproof formula K9 Advantix II is waterproof, so there's no need to reapply after your dog has a bath or goes for a swim I have two German Shepherd Mix dogs. One is 56 lbs, one is 50 lbs. I have a few questions.
1) Should I dose them both at the up to 55lbs, or the 56 lb dog at the 55+ lbs dose or…?
2) I just moved to Florida from MN and have never dealt with fleas before. I bathed them in a flea and tick shampoo about two hours before applying K9 Advantix II. Is it still effective? I have picked about 20 fleas off of each them today, which is almost a week after application. When can I apply another dose?
3) How do I treat the home/yard? I know this is an important step, yet I haven’t heard a safe solution.

Or can I bathe them after I apply it?

K9 Advantix II Dog Flea & Tick Drops is a topical prevention and tick, flea, and mosquito treatment for monthly use on dogs and puppies 7 weeks of age and older. Repels and kills ticks, including Deer ticks (vector of Lyme disease), American dog ticks (vector of Rocky Mountain spotted fever), Brown dog ticks (vector of ehrlichiosis), and Lone Star ticks for up to four weeks. Effective flea treatment kills 98-100% of the fleas on dogs within 12 hours and continues to prevent infestations for at least four weeks and kills fleas before they lay eggs. Larval flea stages in the dog's surroundings are killed following contact with a K9 Advantix II treated dog Repels and kills mosquitoes for up to four weeks Remains effective after bathing and swimming. Convenient, easy to apply K9 Advantix II For Dogs kills fleas which may cause flea allergy dermatitis (FAD). Advantix II For Dogs kills 98-100% of the existing fleas on dogs within 12 hours. Re-infesting fleas are killed within 2 hours with protection against further flea infestation lasting at least four (4) weeks. Pre-existing pupae in the environment may continue to emerge for six (6) weeks or longer depending upon the climatic conditions. K9 Advantix II Dog Flea & Tick Drops remains an efficacious tick and flea treatment following a shampoo, swimming, or after exposure to rain or sunlight. Monthly tick & flea treatment is required for optimal control and prevention of fleas and ticks. Does not expire if package remains unopened and is stored properly according to instructions.

Q: Can I bathe my pets during the month after application?