[quote=gail] My question is to add 1 or 2 and what is the best number and sex? Is their a science to this or does anything go? [/quote]
Good morning Gail-
I'm so sorry about the loss of your cat with kidney disease. A new kitten (or two) will definitely enliven your household!
My main question is how social is your other cat? Is he territorial, aggressive, or accepting of other cats? Usually dogs (who have lived with cats) acept new cats without any problems.
As far as getting one or two, that's really a personal decision. Is your other cat young and/or playful? If so he might enjoy the presence of a rambunctious kitten (who will probably try to engage him in play relentlessly as kittens often do). If he is older and would rather not play all of the time then you might be bettter off getting two kittens at once. That way they'll rough and tumble play with each other.
Regarding sex, well that also depends. Males tend to be a little more outgoing but also can get a urinary obstruction (which females don't get though both sexes can get FLUTD). You will also spend more to spay a female (and especially two) than a male.
No matter what you decide, enjoy your new babies and give them lots of TLC.