There is rumoured to be a 5 hour original cut of the film that includes scenes involving most of the rest of the cast of the TV series. The original shooting script can be found here. It contains most of the rumoured missing scenes. However, the cuts done for the theatrical release would have been made by Lynch himself, and I am content that the release we have here is his true and intended vision.
As for censorship proper (i.e. that inflicted by the MPAA in the US, and the OFLC here), it seems that the distributors were quite happy to have this show saddled with an R rating. Indeed, even upon re-classification this year, the OFLC felt that this show still deserved an R. I don’t really blame them.
As for this release, it appears to be the US theatrical cut.