The Effect>Horizontal Flip should take care of the reverse view of the Frame.
As for the dust, the best course of action is to clean the film, prior to the telecining operation, and is a feature of most professional telecine houses.
Otherwise, one has only two choices, and either will involve a lot of hand-work. One could Export/Share as a Film Strip (think that this option was discontinued in later PrE versions), then Import the individual Frames of the Film Strip into PS for work, Frame by Frame, in PS. This would be Rotoscoping. The other involves doing the same, without the limitation of the Film Strip format, in Adobe After Effects and its Clone Tool. Either is a Frame by Frame operation and requires a lot of time and work.
Cleaning and redoing the telecine would be my choice. Also, this should eliminate the need for the Flipping, if done right.
Are you sure you don't want to just get this video redigitized? Even with all of the fixes, it's never going to look as good as if you had it done right in the first place.
In any event, you can flip your video horizontally by adding the Horizontal Flip effect (from the Transform collection of Video Effects).
There is no real way to clear dust and debris from your video though. You can add a Gaussian Blur to it to try to hide some of this -- but that will just make your picture blurry.