octyal

Pretty much. Use a wide bladed, fairly blunt object to lever the switch at the top and bottom carefully other wise you can mark the dash. Unplug the old, then connect the new one and slide back in to place.

Firstly, the red bit you are pointing at won't be available as a separate item, it's welded to the rear box. Best thing to do would be to contact your local factors, or try the online ones, like ECP or GSF. Put your reg number in and see what they offer. From the looks of it, you have a standard back box, so I would expect to pay about £30-£40 for a new one. As for the cat, universal ones are a waste of time usually, you need to get underneath to measure the overall length, plus the internal and external pipe sizes. Again, see what the local factors say with regards to the cat, they will be massively cheaper than a dealer part. Besides, is it definitely the cat and not just a loose heat shield?
As for the pipe, if it's the convoluted one in your hand, then you could probably repair it temporarily with some tape, otherwise find someone breaking one, or price it up with the dealer.

That will probably because the wheel alignment is now correct. Excessive toe/camber increases the friction on the road