Is there a list of all source geometry attributes (&types) that can be used to control a vellum sim?
EG: friction static_threshold.

Not yet…. I'm making a list and checking it twice, so hopefully it will show up soon.

There is no per-point friction, however, so that attribute isn't on the list.

You can also look at the help for the Detangle SOP to see some of the collision attributes described.

Most dynamic attributes are covered with the POP Attributes docs as there is a lot of overlap.