[PF] Barbarian (Mounted Fury) Build/Questions

[FatherMalkav]

So I'm starting a new game with friends focused on the idea of a mounted mercenary troupe. Where the rest of the group went Cavalier and/or Paladin, I decided to try something different in the form of the Dwarven Barbarian(Mounted Fury Archetype), but I'm new to Pathfinder and wasn't sure if this build seemed viable.

Rotgar Razorback

Spoiler

Dwarf Barb (MF)/4
Ability Scores (after racial/level increase): 16 13 20 10 14 10
Feats: Mounted Combat, Ride By Attack
Traits: Undecided
Rage Powers: Ferocious Mount, Renewed Vigor
Rage Turn/Day: 19 (After Dwarven Favored Class reward)

The character is intended to exemplify the unkillable warrior more than the damage dealing powerhouse, while still possessing the maneuverability of a skilled horseman. I do have a few questions for the more skilled builders/optimizer.

1) Is there a viable mount for a Medium creature other than Horses and Camels available to ECL? The character was designed to resemble a boar, so if something like that is possible it would be preferred, but I only saw them available for Small races.

2) Do traits such as Inspiring Rush or racial bonuses like Relentless apply to bull-rush or overrun maneuvers taken while mounted?

3)Are there any options for equipment, feats, traits, etc. I should take to help with optimization? The only things set are my race, class, and stats.

Please and Thank you to the playground. I can also provide any other information needed.

[Blyte]

Take Overbearing Advance instead of renewed vigor then Overbearing Onslaught, and then the rage power that gives your mount your passive rage powers while raging.

Shoot for your mount qualifying for greater overrun and pick up combat reflexes so you can capitalize on all the AoOs it will generate.