My thoughts:
1. Its crap, but it happens mate. 2.2 owners used to have a near monthly experience until the modified parts were released. Its most likely down to age.
2. I don't know the codes off hand, so will reply seperately with those; but there is no tps warning light. There is, however a TCS warning light, that will flash and light up when the traction control system is activated due to wheel slip. To me, it sounds like your confusing the two?
3. That'll be down to the 501 side light bulbs fitted in the dash. Very simple to replace, and most likely down to wear and laziness on the part of the previous owner in not changing them.
4. Its the idle control valve, most likely causing the problem. On the 2.6's this is the cylindrical metal piece attached to the throttle body. Just remove it, clean it, dry it and replace and jobs a good'un.
5. Sounds like a wheel bearing from your description. If it is, the noise will increase with road speed, and you'll hear it under certain cornering conditions.
6. N//A
7. Check the manual when it arrives. If the leads are correctly made nothing should need modifying - Thats the whole point of purchasing the leads; it does it for you.
8. They're an absolute pain! Its a common MOT replacement, especially on cars doing plenty of miles (loaded up constantly). If your mechanically minded, you can purchase the tools and bushes for under £50 - Then do them yourself saving quite a bit of money!
9. You might be able to mod here. If you don't have electric mirrors, you could have the loom in place to fit them - Its something to consider
10. Vauxhall aren't too bad on pricing for genuine wiper blades - Might be worth purchasing them, least you know they'll fit perfectly.
11. If your running hi-spec calipers (e,g. 4 pot conversion) you should have very good brakes. If they're not that good, I would recommend rebleeding the entire brake cirucuit with new fluid. Unless you've had it done recently its not likely to have been done in ages.
It sounds like lots of teething troubles; but B's are getting on now - Even so, there isn't much in the same size/price segment with the performance and general usability as the Vectra. They're very good cars.