1. Security (partial Auror experience)Incompetent enough to be sacked from the Aurors.
Point.
2. Medical assistance (former volunteer) Depends on what he volunteered to do: I'd much rather employ someone who's drawn blood than someone who's donated it.
He assisted at the Werewolf Clinic, mainly brewing.
The most likely option.
3. Painting and interior restoration (He is quite good at painting squid! It met my approval.) Perhaps, but I doubt a Malfoy would stoop to a caretaking position.