A: You have to be present but, I have on rare occasion used deposition testimony by clearing it with the court first.Talk to the attorney handling it. Another way to do it that would work is to convert the dissolution into a divorce, use the same agreement and only your spouse and witness would have to appear. Keep in mind, the hearing has to be not less than 30 nor more than 90 days so if you are not leaving until 30 days after the filing, you may be able to get the hearing in before you move.
A: The papers have to filed first. Once filed, the court has to have a hearing not less than 30 nor more than 90 days after it is filed. All you would have to do is show up for the hearing. An alternative would be do a divorce with a complete by separation agreement, have her be the plaintiff and make sure it is attached. You could do a waiver of service. That one requires some trust on your part and if you elect to do it that, I'd get an attorney to represent you to make sure it goes as planned.