chipping away is the one stop shop for wood carvers of all kinds. It's a Canadian store but has an online retail store as well. If you called them and told them what you intend on doing I'm sure they'd have a few of bits for you to choose from.
I'm fortunate enough to work 5 mins from this place and I've bought many carving tools from them over the years, great place.
http://www.chippingaway.com/
I'll be going there sometime this week looking for a terrier type bit for my own carvings, I'll let you know what I find.
Axxon, with the amount of amps you'll be drawing during these long carving sessions you'll want a corded model. A battery pack model might work for small projects, but so will a corded one.
I think all of the Dremels come with variable speeds, but if not, you'll want one that has this feature.