fnwc
Explorer
That list isn't explicitly noted as an order of operation - those are just all things that happen at the start of the turn.
I think there was either a FAQ or CS response which suggested that the subject got to choose the order of application, but that's from vague recollections of a thread from months ago.
We've always played it as a combined effect: subtract the ongoing damage from the regeneration, and apply the result to your current hit point total.
I personally just rule that all the effects happen in the same "stack" and you dont' check for character status until all "beginning of the round" effects have resolved. It makes things simpler.