Audting is one of those things that a lot of people just turn on without thinking about how much data can accumulate in a very short amount of time. When I was doing the BLOB remoting thing we would find customers whose audit data was nearly the size of their BLOB data and in some cases more.
So it's one of those features that IMO you should not turn on unless you absolutely need it and only then turn on the events you really want to audit...i.e. have a really good business value reason for turning on "View". Do you need check-in and check-out if you have edit?
As far as controlling audit retention, go to Site Actions > Site Settings > Site collection audit settings (under Site Collection Administration). I personally wouldn't keep more than 30 days.