Older members eh Drakey!
Anyway, welcome Minoltaman (I'm a Nikon fan myself, but there you go!).
The water in the boot is, as has been said, a well known problem and the bumper removal followed by the replacement of the 2 seals under the light clusters will sort this out.
If you have a 51 plate car, then the chances are that you have the original, heavy wiper arm and blade and these do tend to move back and forwards with a bit of a jolt. Take a look at the screen from the outside whilst the wiper is going to see if it's fouling on anything and adjust if necessary.
If you want to change to the later, lighter arm and wiper, it is a reasonable priced upgrade (less than £50 from memory) and relatively easy to do.
As to the vent issue, you'll need to remove the radio to access the 2 screws that hold the central vent in. When these are out, jiggle the vent and it'll come forwards slowly as the clips release. You'll then need to release the hazard wiring and you can then effect a repair.
Alternatively, if you are near Manchester, I'll do this for you.
Cheers,
Mike
