Ask not what your cat can do for you…
To reiterate a few points:
Believe it or not, two cats are easier than one. They keep each other company when you’re away (just make sure you get two who have proven they get along!.)
No one breed or mutt combo can be guaranteed a specific personality . (Well, tortoiseshells are like candy bars: half sweet and half nuts). Some cats you can love all day long and they’ll remain aloof, while others suffer any amount of abuse and neglect (not that you would!) and return nothing but love.
First let me say I can’t object to rescuing a cat from Death Row. But I would also like to plug no-kill rescue organizations. These cats are usually strays living as fosters in a family home. Since their parent sees them in a home environment, it may be easier to get an assessment as to their general personality, charming traits, and bad habits.
Other things to think about:
Are you prepared to spend a good four figures a year on food, litter, toys, and preventative vet care? Not to mention periodic vet trips for accident or illness, increasing as 20 years go by.
Will it bother you that everything you own will be covered in cat hair?
Are you prepared to clean up hairballs,(that reminds me, add cat grass to your list) train them to use a scratching post and put up with the occaisional furniture shredding anyway?
By the way, an adult cat will be easier for a first time owner than a kitten, as one of you will know what you’re doing 
DO NOT DECLAW. Unless you want to chop off your fingers at the first joint at the same time, in which case, go ahead. Or if it’s important to you, get a cat that has already been declawed.
Scared off, yet?