I agree that the W sounds like the focus of the kit, but I think you want it during laning phase before level 6 so maybe keep it on W. I think the other abilities should interact with the frozen minions more. Also, I think this champ should be able to damage frozen minions, but towers and teammates can't perhaps.
The problem with a champ focused on manipulating enemy minions is that it makes them far less useful out of lane. Maybe give the W a second effect that can be used on enemy champions somehow, for example the W creates an icy aoe surface that freezes enemy minions but also causes champions that move into it to slide in a straight line until they exit the aoe and can move again.
I think an ice based monk character could be really cool. Have a think about how you can make his abilities more thematic/interesting. All champs released by Riot these days usually have a really distinctive kit. (Yuumi jumps on champs, Qiyana interacts with the map, Sylas steals ults etc..)