Hi, and welcome to the gang (uhm, community) of avast users!

1. Do I have to make any manual settings or does the standard setup give me optimal protection?

You should be fine with the default settings. They should ensure that you will not get infected.

2. When setting up the programme, I inserted "127.0.0.1", as requested, in my mail programme (Outlook Express 6). How do I know if my mails are actually checked?

How did you set it up, exactly? Normally you’d set it up using the Mail Protection Wizard (no manual setting, just completing the Wiz).

3. I also looked for updates during the setup, as suggested, but to my surprise there were none. By the way, I have a dial-up connection. How can I be sure that the automatic update is working?

Well since you downloaded and installed it yesterday it’s no wonder there are no updates, is it?

The updates should take place automatically. You’ll be notified by a blue box in the lower-right corner of the screen whenever an update is installed.

Hope this helps,
Vlk