Hiya mate. Ive just done this so am happy to answer your questions.
You need a kufatec loom or similar. Halogens have 10 pin connectors and xenons have 12. So you need this adapter to accommodate the change. After this you plug them in and code them in via Vagcom.
And to answer your next question with regards to the headligh level motor, no you cannot retain use of that functionality.
Cheers,
Faz