Why a mask? –
have you considered using makeup?
I love the free hugs shirt! What if you darkened your eyes and "extended" your smile with cuts and stitiches? Bloody of course, maybe a glob of blood for a head wound?
That way you can use dialogue and really entertain as you slide!
As for lower arms, if you go the "crazy" route - take tube socks with the fingers cut out and attach them to your shirt (cheap arm covers, maybe have a "sock friend" on one or more hands?)
Do Vegan Zombies eat heads of lettuce?