Dean,
Yes to your first question... you can really set anything you want to make the redirect trigger... the method your describing would work.
For your next question, just so I understand, you want to collect just the date and then am or pm... meaning you're not collecting the time, as well?
You could bring the two results together if necessary through concatenation, but why not just have two separate columns (one for date and one for time of day)?
Cheers,
Brian