Apoxie or any of the sculpting epoxies will work for the ears. So will Critter Clay as they're relatively small stubby ears to begin with.I'm not sure about your question on the toes. The last digit of the toe will be with the nail or claw down. Mink use those claws and they don't retract like a cat's (the way your diaphragm depicts).As for habitat, you're right on about a snow scene. Mink do live near water but there are LOTS of streams and rivers that have rocky banks. I'd suggest recreating a diorama depicting the habitat in YOUR area so that people who see the mount will have some recognition factor working.As for the prey species, the mink eats anything near the water abode it lives in. PERSONALLY, if I were doing a fish, I'd get one and mount it conventionally so that it would fit the mink's mouth and the pose that I wanted. It's great practice to learn both fish mounting as well as fish painting. You obviously have some artistic talents, so just push your envelope a bit.
Your questions reflect a good work ethic and show your commitment to do things well. Your drawings express your artistic ability, which is generally accompanied by creativity and imagination. That can be a great strength in taxidermy, but one that needs to be harnessed. As an art major in my early years in college, we were reprimanded for "recreating" exact likenesses of anything. In taxidermy, the goal is to be as life-like as possible, to recreate exact likeness. Be sure to use good reference photos (there are tons of them on the internet) to get accurate dimensions and sizes. Use your creativity and your drive for excellence in tandem and you'll do well, I am sure.By the way, you could also consider crawfish, a frog, mouse or a small bird as prey in the mouth. I once mounted a bobcat exactly as it had been shot - its front paw over a dead guinea fowl and feathers hanging from the cat's mouth. Be sure and post pics of the finished product!
Krysta, Im working on one similar and found a few good pics. I hope they help answer some of your questions. Brian Harness did an article in Breakthrough on using the real bones. Skin them all the way out like you normally would to the toe nail, rather than remove the bone leave it intact. You can wet tan the skin and when you go to do the feet, very little clay is needed and the real bones are there so you can position the toes accurately. When I get into the shop ill look and see what Breakthrough issue it was and let you know. Its a good read. I love the action in a pose like this.
It looks as if that neck is too long as well. Remember, vertebrates only have 7 neck bones and I just don't think a minks are that long. I may be wrong - it won't be the first time, but it just appears that way. If I'm right, the neck isn't too thick. Shortening the form will allow the hide to expand.