Averlanders are one of my fave warbands. Like most human merc bands, they're deceptively strong if run properly.
Maxed heroes and 11 bodies are a good start. I realize you may be picking your equipment with models in mind, but personally I'd start with nothing fancier than hammer/mace-dagger for melee. I'd drop the swords, shields and axe (especially the axe and shields), add a crossbow for the Captain, and put the rest into more Mountainguard bodies. You should have enough gold for at least one more
MG.
Mountainguards are *great* human henchmen because of the WS4. That means the first
WS/
BS boost gives you a good dilemma -- do you make them WS5 henchmen (which is great), or go with
BS and get them bows, since WS4 means you probably won't be at a disadvantage versus most henchmen in the game if you end up stuck in. Personally, I like to run at least two solid groupings of
MG so I can do both.
The rubber hits the road when the Captain and Bergjaegers start getting Shooting skills. At first the Youngblood will need to be more targeted for melee duty (more accurately picking off stunned opponents, etc to get cheap experience points), but with a few increases, he should become a viable shooter also. Gorgon's rule is that if a character has access to Shooting skills, it gets them ASAP, and Quick Shot is the first skill since it doubles your output.
While your heroes start getting shootier, you get one unit of
MG to BS4 like I said and then pass out the bows. That makes them a great flex unit capable of castling up and shooting with the heroes and halflings, or pulling out their maces and getting stuck in with their WS4 if your opponent gets close. Down the road, don't forget hunting arrows for the Bergjaegers.

They kinda balance out the S3 compared to S4 crossbows.
On the mini front, I think your choice for Bergjaegers is perfect. I'd just convert regular State Troops to serve as Mountainguard. Remember that Averlanders tend to go into battle looking good, so don't sweat the frilly stuff in a Mordheim environment.
Best of luck to you!