>1. I choose "Updating site" and interrupt this update.
>What option should i use next, when i want to 
continue?>"Updating ..." or "Continue interrupted ..."

- If you have restored the previous cache: use update
- If you discarded the previous cache: use continue

Continue will not check all documents and files for 
update. With a "fresh" cache, you may choose continue

>2. I have mirrored a site with about 12000 links. When
>updating this site i have some problems. It takes 
>about
>60-70 minutes for HTTRACK to scan/parse the local 
>files
>?! To many files ? Slow CPU (i have an pentium III 500
>MHZ)?
Yes, update means that EACH link will be tested for 
update. If you have 50,000 files, this will generate 
50,000 update requests on the server ("Give me the 
file /foo.html if it has been modeified since ...")

>3. After downloading the site, about 500 files where
>missing. It would be a GREAT feature when HTTRACK 
>would
>have an option like "download/retry failed links".

Use retry feature (set it to 5 or 6 if you want)
..and look at the hts-log.txt file! :)