Thanks for your question! Great to hear you are happy with your un-cover up 00.
As for you question about invisible tan: the more you use it, the more tanned you'll get. Since you're quite pale yourself, I would not apply it too often, so that you just get a healthy glow instead of looking like you spend a week in a solarium :D
Also, don't forget concealers usually need to be a shade lighter than your foundation (but with the same undertone). Therefore I would probably recommend rms un-cover up 22.
Hope this helps and greetings from Berlin!
You don't really have to be careful, haha. It won't go that fast :)
Yes I would still recommend the 22. I think if your skintone is that pale that you normall use uincoverup 00, 33 might become too dark and maybe unnatural looking.
Since you are very pale, I would also recommend you to use a sunscreen or Moisturizer with SPF like Kimberly Sayers. Or another idea is to use a tinted moisturizer / BB Cream with SPF instead of or next to the un-coverup.
You might want to look into Luxsit BB Cream, ILIA's Tinted moisturizer, or even HIRO Foundation - these all provide an SPF.
Oh this article might also help you: http://amazingy.com/magazine/swatched-natural-foundation-and-concealer/
You're welcome! :)