Answers...
Phew! - thanks for the comments, I didn't realise that one day I'd actually post something useful!
Let's look at your questions then...
i) Covering Letters Spiral Dive. Yes, of course. A CV without one is like a phone call without the "hello". Short and sweet is good, as you're going to print the information again on the CV. But you can fit your licence and type rating details onto one line. I won't stop on your covering letter though, like I said, I always read page one!
ii) On that subject you can put something about the company in. It'll make me a bit more interested in your CV when I see you've made an effort. But read it, and get someone else to read it. Your comment about how you spent £XX,000 on your licence because "...the King Air was the only aircraft I ever wanted to fly..." will probably have the same effect on me as it just did on you when you read it! I.e. "Yeah, yeah, NEXT!"
iii) As WWW said, if we're not advertising then it is courteous for us to reply, but it is unsolicited mail after all (I know, harsh but fair) so it's not a black mark against us if we don't. If you want to confirm that it's been received feel free to put in an SAE or postcard in. I don't think many companies would be cruel (stupid!) enough to not just pop it into the post room. You can try and ask for some checkboxes to be filled, but know from my own application experience that it may not happen - you'll just get a blank card back.
iv) Your CAA Reference Number has no bearing on me! We'll get it from your licence, assuming you sent in a one page CV ;o)
Good luck.
Dai.