@1:
The Gateway and DNS entries must be correct, otherwise the manual time update or the antivirus update wouldn't work. Also a test email can be send out.
The time should be updated every 12 hours? I will keep track of it.

@2:
OK, thank you.

@3:
DNS and gateway are correct. It's the IP of the router connected to internet via DSL/calbe. Two days after the manual update of antivirus database and the option 'Now and every 24 hours at 0:00' the database was not updated. The content of 'freshclam.log':

--------------------------------------
ClamAV update process started at Thu Oct 19 23:35:09 2006
SECURITY WARNING: NO SUPPORT FOR DIGITAL SIGNATURES
See the FAQ at http://www.clamav.net/faq.html for an explanation.
main.cvd updated (version: 40, sigs: 64138, f-level: 8, builder: tkojm)
WARNING: Your ClamAV installation is OUTDATED!
WARNING: Current functionality level = 7, recommended = 8
DON'T PANIC! Read http://www.clamav.net/faq.html
daily.cvd updated (version: 2051, sigs: 9395, f-level: 8, builder: ccordes)
WARNING: Your ClamAV installation is OUTDATED!
WARNING: Current functionality level = 7, recommended = 8
DON'T PANIC! Read http://www.clamav.net/faq.html
Database updated (73533 signatures) from switch.clamav.net (IP: 130.59.10.34)
--------------------------------------
ClamAV update process started at Sat Nov 4 10:44:37 2006
SECURITY WARNING: NO SUPPORT FOR DIGITAL SIGNATURES
See the FAQ at http://www.clamav.net/faq.html for an explanation.
main.cvd updated (version: 41, sigs: 73809, f-level: 10, builder: tkojm)
WARNING: Your ClamAV installation is OUTDATED!
WARNING: Current functionality level = 7, recommended = 10
DON'T PANIC! Read http://www.clamav.net/faq.html
daily.cvd updated (version: 2161, sigs: 1600, f-level: 9, builder: arnaud)
WARNING: Your ClamAV installation is OUTDATED!
WARNING: Current functionality level = 7, recommended = 9
DON'T PANIC! Read http://www.clamav.net/faq.html
Database updated (75409 signatures) from switch.clamav.net (IP: 130.59.10.34)
--------------------------------------
ClamAV update process started at Sat Nov 4 10:48:24 2006
SECURITY WARNING: NO SUPPORT FOR DIGITAL SIGNATURES
See the FAQ at http://www.clamav.net/faq.html for an explanation.
main.cvd is up to date (version: 41, sigs: 73809, f-level: 10, builder: tkojm)
daily.cvd is up to date (version: 2161, sigs: 1600, f-level: 9, builder: arnaud)
and after manual update:

--------------------------------------
ClamAV update process started at Thu Oct 19 23:35:09 2006
SECURITY WARNING: NO SUPPORT FOR DIGITAL SIGNATURES
See the FAQ at http://www.clamav.net/faq.html for an explanation.
main.cvd updated (version: 40, sigs: 64138, f-level: 8, builder: tkojm)
WARNING: Your ClamAV installation is OUTDATED!
WARNING: Current functionality level = 7, recommended = 8
DON'T PANIC! Read http://www.clamav.net/faq.html
daily.cvd updated (version: 2051, sigs: 9395, f-level: 8, builder: ccordes)
WARNING: Your ClamAV installation is OUTDATED!
WARNING: Current functionality level = 7, recommended = 8
DON'T PANIC! Read http://www.clamav.net/faq.html
Database updated (73533 signatures) from switch.clamav.net (IP: 130.59.10.34)
--------------------------------------
ClamAV update process started at Sat Nov 4 10:44:37 2006
SECURITY WARNING: NO SUPPORT FOR DIGITAL SIGNATURES
See the FAQ at http://www.clamav.net/faq.html for an explanation.
main.cvd updated (version: 41, sigs: 73809, f-level: 10, builder: tkojm)
WARNING: Your ClamAV installation is OUTDATED!
WARNING: Current functionality level = 7, recommended = 10
DON'T PANIC! Read http://www.clamav.net/faq.html
daily.cvd updated (version: 2161, sigs: 1600, f-level: 9, builder: arnaud)
WARNING: Your ClamAV installation is OUTDATED!
WARNING: Current functionality level = 7, recommended = 9
DON'T PANIC! Read http://www.clamav.net/faq.html
Database updated (75409 signatures) from switch.clamav.net (IP: 130.59.10.34)
--------------------------------------
ClamAV update process started at Sat Nov 4 10:48:24 2006
SECURITY WARNING: NO SUPPORT FOR DIGITAL SIGNATURES
See the FAQ at http://www.clamav.net/faq.html for an explanation.
main.cvd is up to date (version: 41, sigs: 73809, f-level: 10, builder: tkojm)
daily.cvd is up to date (version: 2161, sigs: 1600, f-level: 9, builder: arnaud)
--------------------------------------
ClamAV update process started at Mon Nov 6 22:14:07 2006
SECURITY WARNING: NO SUPPORT FOR DIGITAL SIGNATURES
See the FAQ at http://www.clamav.net/faq.html for an explanation.
main.cvd is up to date (version: 41, sigs: 73809, f-level: 10, builder: tkojm)
daily.cvd updated (version: 2167, sigs: 2029, f-level: 9, builder: ccordes)
WARNING: Your ClamAV installation is OUTDATED!
WARNING: Current functionality level = 7, recommended = 9
DON'T PANIC! Read http://www.clamav.net/faq.html
Database updated (75838 signatures) from switch.clamav.net (IP: 130.59.10.34)
It still seems not to work automatically...