Winter tyres and wheels STI 2018 model?

[M030ef00]

Hi, I'm thinking of getting winter (or all season) tyres for my STI but I could do with some advice:
Which are the best winter tyres for the STI?
Does anyone have any experience with putting smaller/steel wheels and crossclimates on?
What wheels are best?
If you go R17, what tyre size do you use, and do you have to alter suspension etc?
Has anyone tried Wintercontact 860s?
Any reasons not to?

Many thanks