To be 100% legal, HID headlights need to be auto-levelling and have headlamp washers.
However many people have fitted aftermarket kits and not bothered with either and don't seem to have had a
problem, so long as the headlights are correctly aligned.
To fit the washers you would need (at a minimum):
1) New bumper
2) 2 x washer units
3) Pipework and brackets etc
4) Bigger washer fluid tank