A good place to start with upgrade is this FAQ http://www.adobe.com/solutions/customer-experience/enterprise-platform /faqs.html.
We've put a lot of focus on the upgrade of LiveCycle document services to ADEP in this release. There is very little in the way of architecture changes for document services in the ADEP release making the upgrade relatively easy.
We have also created an Enterprise Readiness Tool to help evaluate your environment prior to upgrade so that you can more easily plan the upgrade steps. More information is available here - http://help.adobe.com/en_US/enterpriseplatform/10.0/UpgradeChecklist/i ndex.html.
We are in the process of rolling out the upgrade documentation and are in the final review stages of some additional documents. Some were just posted in the last few days. You can see the upgrade documents here - http://help.adobe.com/en_US/enterpriseplatform/10.0/documentation.html #task=2&module=-1.
Hope that helps.