Hi again Delta.
You should be able to find a stereo easily enough on
that'll do the job. I got a CD player for mine off a Clio that works a treat. It sounds great with the rear speakers in.
Persevere with those clusters! I've spent god knows how long fettling, sometimes making it better, sometimes worse, it's a boring job though isn't it? Front fog lights should be fairly strightforward to fit to the bumper. The black spaces in the bumper I think are removable so you can clip lamp units in their place. Wiring them up to work howver might be difficult, as the front fogs are switched from the indicator stalk, so I would think you would need the stalk, wiring, relay and fuses. Sounds a pain to me, though the front fogs do look smart, even if you can't use them!
I've had a look on GSF for you for a radiator, they are £65 brand new including VAT delivered. Though I think you'll be able to get a decent second hand one from a breakers for a bit less. A new water pump from them is a tad under £40 including the VAT. The coolant tank can be washed out, though I couldn't get all the crud out of mine. You could always get one from (you guessed it) the breakers thats cleaner.
I've attached a rubbish quality a piccy of our car from ages ago, best I can do without a camera!