I think so, but I don't recommend it. Having a history of when and from where customers log in can be useful in audits.
Yes, but there are some logs that are not rotated intentionally, like the mail log and user logins. The mail log has the tendency to get the largest, but has a complete history of all email each customer received, which can be very useful.
Only the retention policy (number of days to keep logs), as Mike mentioned earlier in this thread.