In te buy/sell Pool frame I always see 0 even if I click update values.
Is it normal?
usually is normal because CAT use all the available amount in the buy/sell pool. (You should find in the market log a message like "Try to create new PIng From Pool"
The UPDATE command is to change the pool value to another you prefer, for example 0.1 BTC if you want to let CAT use 0.1 BTC to create new ping.