Are these a direct fitment? And does anybody know if they will fit under the standard 17inch vRS rims?

Thanks

Yes they're a direct fit. You will probably need spacers to fit them under the standard 17's as although the diameter will be ok the calipers protrude quite far so depth inside the wheel is the problem. Bengie has them behind 17" VW Santa Monica wheels with spacers I believe.

second question, is the cost of the conversion worth the benefits?

..could be interested in the mod.