Q: …The problem is that RPManager keeps overriding the settings I've set up in the main 3dsmax render dialog. The render setting keeps being switched off, and I've tried switching it on with or without having the RPManager window open, but it keeps getting reset when I click render. What is the correct procedure when you want to remember these non-RPM render parameters?
A: The correct procedure is to open RPM, restore one pass (just one), then edit the controls in the main 3dsmax render dialog. When just one pass is restored, the main render dialog is 'connected' to the RPM stored render data, so any edits there should work. If more than one pass is selected in RPM, this will not work: there is no connection. If you simply open RPManager without restoring a pass, the connection with the main 3dsmax render dialog does not exist, so make sure you restore a pass.
Q: How do I capture/restore vray object properties?
A: To do this, add the object to a capture set that has the 'UserPropBuffer' assigned (it is in the right-most column). This is where vray stores its object properties (if you open the 3dsmax object properties dialog and check out the 'user' tab, this is the data).