No, every lookup C.A.T. will re-calculate all the values, so your "*TopOfCurrentOrderBook Price *MINUS *0.5%" will be updated with current values.
If you use 100% Of your balance yes. But i think that any person who use CAT decide to use a percentage (for example 0.1 BTC) on 1 Market and then another quantity on another market.
There are person who trade on over 100 market without problems.
C.A.T. use only the Amount you set in your PING Orders : if your total ping amount is 0.1 BTC, CAT won't use more than this. Only the rounding routines could use a little more of your portfolio to adequate the order calculation. But you can disable this option.