I like all that. 1 minute is a fine duration for the fear, and CL doesn't matter for domination as we've modified the range and duration (the only things CL-dependent in the spell). We might as well use CL=HD.
Agreed to any cold land, no treasure, tracking by scent. We may even want to give him keen scent, ala dire sharks.
CR 20 sounds good, but his AC is really low for that CR. It should be mid 30s, not mid 20s. How about boosting natural armor up to +13 and giving him unearthly grace?