As there is no formal guide (as far as I can tell) I think I'll pitch in and tell you what I've learned so far about the game in terms of competing for that #1 Spot on the Leaderboards (you'd better take notes, dustin).
When you start out, you have the option of choosing any combination of cats that you would like to have. They can be toggled in the bar on the right side of your screen; shaded means not selected, while colored means selected. Then simply click on Survival instead of Adventures.
I highly recommend starting with just Jazz



I very highly suggest you only start out with one cat, whichever one it may be. This is because in survive mode your score is calculated by (Base Score/Number of Cats at the Start). That means if you start with two cats your score will be cut in half regardless of how long both cats were actually in play. Your base score is divided by 3 when you begin with 3 cats. Starting with multiple cats is hardly worth that kind of penalty since it is hard to focus on both cats at once. In addition, you can earn 'bonus cats' as you play, which practically negates any advantage you get from starting with more cats (more on that later though).