Eddy
2
Welcome to this board.
1] You will notice it for sure if Avast had found something.
2] Log file is in the Avast folder, or start Avast > Menu > Log viewer
3] See 2
4] Avast checks for updates when first connected to the net (eg: after install, reboot etc). After that Avast checks every 4 hours for new updates. You can change this behaviour in the Avast4.ini file.
I suggest you take some time to get familiar with Avast and its settings. Read the Help/Manual and have a look HERE. This will answer already many of the questions you have.