If a feedback comment was created in week 24 for a class of styles on a specific measure, how long does the feedback remain? We are in week 31 and the feedback is still there. How does this work?

The feedback is linked to Time and to whatever other dimensions were being viewed when the Feedback was entered. Note that depending on your default time level (e.g., year, quarter, month, week) you'll see the feedback until that period has ended. PMF will show feedback that's linked at the lower Time level at the higher level of time if they're still in term. So if your time level viewed is quarter, you'll still see the feedback until either the quarter ends, or another item of feedback is entered for a more recent time during that quarter. After the quarter is over, the feedback will be history.

Hope that makes sense.

One additional note. Feedback includes a "show related feedback" feature - a checkbox on the feedback panel. If you click it, you can continue to see feedback even if it's at a higher level dimension-wise (provided your access security allows this) or it goes outside time-scope. Some people like this, others don't care.