Im am a poser animator and any program that assists in animating poser characters is of interest to me. Many of the features you describe already exist in a powerful program called "lifeforms" from credo interactive Such as opening any poser figures bone structure and animate it with being hampered by the geometry you should also include the ability to preview BVH files BEFORE opening them as you can in Lifeforms. the walk desiger in poser now is basically obsolete for the newer characters so a designer that uses the bone structure is best. you should incude the ability to smoothly blend animation from different sources with blend Zones as you can in lifeforms. and you should include the abilty to create walk paths that change altitude so the characters can easily walk up stairs or down hill as you can in Lifeforms and the ability to reverse a characters foot steps making him walk backwards as done in lifeforms would be nice also. thea ability to recall animation data from an existing library of motions( like head turning and other gestures)already exists in the propack but not all users care to own the propack so you can tap in to the market.

Keep us posted on your progress

My website

YouTube Channel