Does anyone know if I will I get my Winter Coupon back if I refund the game I bought with it?

The best thing to do is to contact Steam Support.

Probably you will get the coupon money refunded in your Steam Wallet.
Or in the worst case, don't get a refund at all.

I think normally you should receive your tokens back for the refunded purchase, so you can buy another coupon. Just take a look at your token balance. ;)

I got my coupon back twice by separate refunds.

I had to click "redeem" again each time, but it was no hassle. Just refund and the rest is automatic.

What about the stickers ? the free quest was bugged for me first day and I redeemed for 500 tokens the Angry Yule Log
a few days later when I redeemed the free sticker, lo and behold I got the same Angry Yule Log
I just submitted a support ticket for this one, not sure if they would refund the tokens.. could get 2 levels if they do quick enough :/