The rust will need to be dealt with by a body shop. The boot lid will need to be removed to facilitate this but its quite an easy repair in my mind.
Is your car a manual or is that some modified auto lever? The reason I say this is the fact that the surround you have there appears to be from an automatic and is not a manual surround. This is likely why the leather gaiter isn't attached. The manual shifter has a plastic bit below the gear knob which holds the gaiter in place and facilitates the reverse gear select. Furthermore, the auto selector surround was never designed to have a leather gaiter, so not sure how it is attached at the base either, if at all?
The weather strip on the headlight can be easily repaired with some mastic or other type of waterproof glue. Ref getting hold of a spare strip there are plenty of people on here with old headlight units who might be able to help. Might be worth contacting Dude, Keron or LeeP or Paul W to see if any of them have this part spare hanging around.
I'm sure one of them will come through for you.
I'm afraid I can't comment on any performance impact from the dented exhaust, but I would say if there was any it would be negligible.