Cron and import process - quick questions!

Iam using cron to parse a log file (that is being imported via rsyslog from another server).


a.) I found that piwik does not memorize the last time it ran so that it does not parse duplicate log lines. Correct?
b.) If so, what is the recommended way to parse a log that is imported in this way so piwik does not confuse itself?
c.) Is it possible to do an import/archive process every hour or less?

a) yes
c) yes