1. What's the process for using PPPro, Universe 5.0.1 and Renderama under OSX?

The following procedure should be used for all versions of Universe:
a. If you haven't trashed the PPProPreviews folder in a while, trash the folder.
b. In the PP Pro Preferences Tab, switch to "Advanced Preview". Note the name of the Previewxxx folder. This folder is a subfolder inside the PPProPreviews folder.
c. Close the PP Pro interface.
d. In Animator, run a preview of the entire animation from start to finish.
IT IS IMPORTANT THAT YOU DO NOT REOPEN THE PP PRO INTERFACE BEFORE DOING THE NEXT STEP.
e. Copy the PPProPreviews folder and the subfolder Previewxxx onto EACH system that is a slave of Renderama. Place the PPProPreviews folder in the same folder that the slave Camera resides on the remote system.
f. Create the Renderama job using the Render Setting window in Animator.
g. Run the Renderama job.

The Advanced Preview files contain the information that each remote PP Pro needs to render the specific frame that Renderama asks for -- information PP Pro cannot get from Camera.

2. Does the constraint on positioning child objects of PP Pro at (0,0,0) still apply to PP Pro 2.1.8 and Universe 5?

No. The constraint was lifted with PP Pro 2.1.6 and Universe 4.0.7. In addition, there is no longer any constraint on the linkage between PP Pro and its children, or its parent. You may set the linkage between these objects as you wish.