Jac - With regard to your oil options, I think the Castrol 0W30 (made in Belgium), a 5W40 that meets spec or the M1 0W40 New Life are all fine choices. There's a post somewhere here on the forum regarding MB back-spec'ing to 5W40. I've used the Castrol (referred to as a "thick" 0W30) with no issues.

We love our Mann fleece filters here on the forum, but the Bosch equivalent in N. America is part # L3477.

The Mann air filter is #1120940304 and you'll need 2.

It sometimes helps to use a 2003 MB SLK320 as the reference vehicle when doing parts searches.

needswings.com, autohausaz.com and pelicanparts.com are all good parts sources and offer international shipping.

Good luck with your new ride!