OMG, it sounds like there are some very dysfuntional cats out there!
I have 2. Both 4 1/2 year old moggies.
Vets Bills : Same as a dog really
Litter tray : Dump the whole lot in a bin bag every 3-4 days and rinse the tray with non-bleach multi-surface cleaner. A lidded tray will smell less, and I carry the tray to the bath and use the shower to rinse it out.
Getting run over : I live in a main road, so they're mainly house cats. They are fine to come in and out through the kitchen window (faces the back; I live in a flat, this is the only reasonable access point) whenever someone is home to supervise.
Furry creatures : We had a run of these summer last year. Turned out there was a rat problem behind the shops downstairs and the council dealt with it - no more small furries 
Meowing at stupid times : ignore. They soon learn.
Sleeping in the worst place on the bed : shut the door!
Other misbehaviour : mine are very responsive to the word "NO!". They also answer to their names (Mango managed this int he vet surgery the other day - PFB moment!!)
Mango, the ginger one who's pic is on my profile, is currently in the system to become a Pets as Therapy cat. The vet reckons he is part ragdoll, as he is so floppy" when he's picked up.
There are downsides to owning any animal. Only you can decide what the upsided are for you and your family
PS I got my cats because I was refused pets as a child. "When you're eighteen and have a home of your own you can do as you please" So I damn well did 