You can get the spacers from ECS tuning which is a forum sponsor or any other place. H&R makes a complete set with everything you need.

I don't run any and the rear looks a little funny since the wheels are really tucked in there. OTOH, it keeps the crud where it belongs.

Here is a pic from LeMansX5 with 87 reps and no spacers (mine look tucked in like that)


And here is one from ncx with Style 58s and 30mm spacers in the rear


And Xoutpost with Style 99s and 30mm H&R spacers


I only mentioned the snow tires since you have a set of dedicated rims. It seems to me it would be a good combo between this and your summer setup.
We have 20" Toyo Proxes for Spring/Summer/Fall and 18" Blizzaks for winter and I like that combo. A little more "wiggle" with the snows but much more grip at lower temps.
But, it also depends on how much winter driving you will do and how cold it gets over where you are.