Welcome to PADS Ron! You've made a great choice by coming over from Cadence.
I'm sure you'll get a technical response here shortly but, while you're waiting, why not join us on LinkedIn, http://www.linkedin.com/groups?gid=2709886, or sign up for our brand new Twitter feed, https://twitter.com/PADS_PCB? They're both great ways of staying in touch with all the new things happening with PADS.
China GFW blocks most of the social communities you listed. Would Mentor consider to join Chinese communities like Wechat which having 700
In PADS you can create plains as positive. In Setup select Layer Definition where you can select any layer and change to Split/Mixed plane(Split/Mixd is a positive plane). One you have done that, you can assign one or more Net names to this layer and split it into different shapes for each net. Once you move a trave, via or a component, you will re-fload the plane that will create appropriate clearances. If you do not re-fload the plane, during Clearance check it will flag you and you will know that you need to re-fload.
If you have additional questions please contact Mentor Customer Support or visit Knowledge Base where you can find Techinal Notes and Videos addressing customer questions.