Just to comment on the leash aspect. Most cats do not like harnesses much less leashes. They seem to be more independent then dogs (let's not get into a dog vs cats thing, I love them both but love kitties more!). The first time we tried to leash Beau our beloved and vastly intelligent tuxedo cat, he ran into the middle of a patch of poison ivy and lay down. We referred to this as taking him for a drag. He did become used to a leash and we did get him used to it. He and DH used to take a stroll around the campground loop in the very early am before folks got going. He would walk without the leash, btw.
Right now we need to either find the figure 8 harness we've used for our last 2 cats or buy a new one for our newly rescued dumpee, Sugar Ray (my avatar photo). He is thought to be about 3 or 4 years old and we need to throw him into the van and see how well he'll travel. We have eventually been successful in leashing all our cats who've traveled with us, but Ollie always used to look at the leash trailing behind him as if it were something following him. We always used to be very close by so it seemed better to let them walk freely, tieing a cat up usually resulted in Mr. Houdini backing up to till the leash was tight, wiggling 2 times and running free. At least Beau could do it.