A: Yes, if you go to the contact card > edit you can remove the bounce with Unbounce address under the e-mail field. The button is only shown when the e-mail has hard bounced. Note that the e-mail might bounce again depending on the reason for the bounce.
You can unbounce up to 2% of the contacts in your account each month (at least 1). When the limit is reached, the button is greyed out and shows No more emails can be removed from the bounce list this month.