1. How can I know for sure that I found one bitcoin block, where would it first show? (unconfirmed balance?, transactions tab?, listtransactions command in console?, debug.log, exact path, exact thing to search, what each logged syntax means)
It will show on the transactions tab instantly. It will also show in listtransactions. It may also show elsewhere but I have never cared to look.
2. How long will it take (in hours and new blocks found by the network) for the 25 BTC reward of the found block to find their way into the wallet's balance ? (the minimum wait time, the average wait time, the maximum wait time)
It will show instantly. It will be spendable and added to the confirmed balance after exactly 120 blocks (the protocol only requires 100 but the QT client adds an extra 20 blocks).