I tried the wonderpay module, but i kinda like using the ubercart cart to review before redirecting to the PayEasy site. Also, the PayEasy site doesn't really handle data not related to the payment, so it wont be able to return data aside from the payment details.
edit: ps. im using the 2checkout module as my pattern.
edit again: pps. also, i want the PayEasy module to play nice with other payment modules. i dont want it to be the end all/be all payment module for a store. the customer should be able to have various payment methods on the store. hence the idea of putting the billing as a "pop-up" only when the payment module requires it.