You dont need the higher din necessarily. they are just a little more burlier (jester has a couple metal pieces). I would say get pair of fks 120 or pivot 12's, way more durable. Will hold up better if you gain some weight too
and i mean, its longer, so i guess? but not noticeable. Trust me man, like i said, im small and riding 171 blue steeles which measure true so they are longer than most other skis. As well as the blue steeles, the halos have rocker, so they ride short. Trust me man, you need a 182 without a doubt. 170 will be way to unstable and just short in general for you