My 97 Jetta has the 1Z, and its OEM dipstick is orange. I've never seen a yellow one, but I haven't seen a lot of 1Z's either.
Rammstein, if you're talking about the 4 Audi pics, and the hose in the first pic, isn't that rad hose?
Pic 3 of 4 shows the air route fairly clearly, airbox > MAF > turbo intake > turbo outlet > intake manifold.
What yr Audi is that?