Don't know when packages will be available. JPVonDrake can help you there when he sees this thread. Or you could call Pam or Marie at Kingdom Konsultants. They do extraordinarily good work. Kingdom Konsultants is an official sponsor of this site. Otherwise, just look for Kingdom Konsultants or WannabeBelle here.
As for crowds in April, that's not so good. Not sure when Easter is next year, but if your trip is anywhere close to Easter it could be pretty bad.
Disney rates now are structured such that from late February to late April is the most expensive time to visit, except for the week betwen Christmas and New Year's. What you're looking at is a spring break crowd, whether from northern colleges that tend to have later breaks, to most public schools, that aim for the week before or after Easter. (Many southern colleges tend to aim for early march for spring break)