Puppy-proofing the cats... How does that work?

[mrs.b]

This is probably a dumb question, but we've never owned cats and a dog at the same time, and few of our friends have, either. The few that have adopted older dogs that somehow magically knew to keep their noses out of the cat "things." Since we will be getting a puppy soon, we are making the necessary preparations of reading up on training, collecting supplies and finding homes for those items, puppy-proofing, and familiarizing our cats to the changes.

Our cats are rescue "mutts" but they must have some Maine Coon or Ragdoll in them. The female is 15-lbs and the male is 20-lb. The male could lose a pound or so, but both are fairly fit beyond that; it's all length and height. We cut a hole in our laundry room door to give them access to their cat box a few years ago, but the pet door big enough for them is easily big enough for a puppy until it is almost full grown. Dog-proofing is difficult when our cats are bigger than some dogs. Where do most people put this stuff to keep their dogs out of cat food and "stuff"?

Also, training... I know it's odd but I've been "training" my cats. It started out as a silly game when the dog-training clickers arrived, and since I do not have a dog yet, I used what I had. Oddly, my cats have taken to it! The male is only willing to follow a lead over obstacles, but balked when we got to commands. The female, though...she's a pup at heart. She follows a lead over and around obstacles, and does "sit," "stay," "up," and we're working on "down." Next is fetch. What are some trick/games I can eventually train my cat and future dog to do together (once we have the dog and it's caught up to the kitty in ability)?

Edited to Add: We entertained the idea of putting their food and water in the laundry room since it's already somewhat secured (not really, but it would only be one door we would need to monitor access) but it is a small laundry room, so we do not want to put their food too close to their box and risk them deciding to not use one of the two "stations." I also considered toilet-training the cats so just their food/water could be in there, but...no. Something just feels gross about sharing those facilities with the cats.