The sideskirts come with double sided sticky foam already on them but it is worth getting the fitting kit but not the strips. They push into holes in the chassis and allow some extra security.
Part Numbers for the skirts are - £82:
1K4 853 859 B9 B9
1K4 853 860 B9 B9
These are the black textured ones, not primed.
Adaptors - £16.50:
1K0 853 493 x4
Screws - £3:
103 546 02 x10 (probably won't need 10 but I bought some spares).
Items 10, 11 and 12 you want.
Hope this helps.