Products we use and recommend: 

Toys: Donut ball toy or ball tower
Cat wand with no string, they will chew through it, either rope that attaches toy or toy is attached at the pole and hangs long, etc
Laser- battery operated 
Scratching post 
Cat tower

Other: 
Pet carrier for adoption transport & vet visits
Cat nip package for stressful situations – for original integration into new space, for travel, vet visits

Food: 
For kittens – free feed (gravity feeders)
Adult cats – depends on weight, whether free feed or regulate
Dry food, Low grain, high protein, don’t skimp on food
Brands we use:
Tiki Cat, Orijen, Nulo, Taste of the Wild, Blue Buffalo, Evolv, Acana, Wellness…

Litter:
Type we like: Scent Free. Purina TidyCats Lightweight or otherwise clay-clumping litter
Litter box: We prefer a box with lid but no door for ease of them and us
Litter scoop: Litter Genie Plus with refill off-brand bags

Warnings:
Some essential oils and houseplants are dangerous
Don’t give your cat dairy

Should your cat be indoor / outdoor or indoor only: 
Traffic, is the cat likely to get hit by a car? Likelihood pet will be stolen, is it a kitten, special breed, or unique color, or especially friendly? Predators, are there owls, eagles, coyotes, roaming dogs? Potential for injury from feral cat colony or neighbor’s cats?

If outdoor:
Chip
Breakaway collar with bell

If indoor:
Cat scratch post
Toys & enrichment
1 litter box per cat
Air purifier

Integrating a new cat: 
How to do a slow intro and why- They said it best here. Feliway spray – this pheromone-emulating spray mimics the natural pheromones released by a mother cat to calm her kittens. It helps with spraying & fighting.