A lot of people replace the runflats for normal tyres, with a popular choice being the Falken FK-452. It's about 90% of the performance of more expensive brands, but a lot cheaper to buy. I personally found the sidewall FAR too soft though, and would have happily gone back to my RunFlat tyres in a heartbeat. What you may want to consider is fitting some of the newer generation RunFlats, which other members on here have done and have been very happy. The standard fitment RunFlat tyres are a very old design now.
I wouldn't personally bother putting RunFlats on your winter tyres, unless you feel you need the added security of not having to deal with a possible puncture during the winter.
As Hutch has said, Bluetooth isn't pre-wired in the UK cars, so it's an expensive retrofit - Really not worth the bother, unless you really need/want it, and don't want to use a Parrot or similar (the product, not the bird).
The stubby aerial... Quite a few people have complained about poor reception, and if you're in a poor reception area as it is, you may notice the difference. I had a stubby on my previous 3.0si Coupe, and it was absolutely fine. No degredation of quality whatsoever. I've also got one on my new M Roadster, and there doesn't appear to be any problems (but I have only just got it). That choice will come down to how much you like to listen to the radio, and how much you hate the look of the standard aerial - I personally couldn't live with the standard aerial, even without any radio reception!
Hope that helps.