Yes. Some revisions will be made to it... Now, actually.
No, but you get to punch people with fire. I fail to see how lobbing a ball of flame compares to that.(B) Can it be used in concert with Spellshape Strike? If (A) is true, then this just seems like a logical follow up question for the Magician archetype. Most spellshape attacks are ranged touch attack anyways and they have far better range increments than Bolt of Justice.
Nope. You only get the initial SoJ element for your Breath Weapon.
EDIT: Question about Combat Theme (Draconic) + Dual Justice
Would Dual Justice grant you an extra type of damage for the breath weapon? Not necessarily at the same time like SoJ but the option to switch between Type A and Type B. Although you could possibly make a special exception for when the paired elements share the same type of AoE--Fire/Cold for cone and Acid/Shock for line--to be mechanically compatible to do 50/50 typed damage.
Each applies only to one instance of Sentai's Weapon. That will be specified.EDIT 2: Question about Enhanced Weapon
If I were to pick one of the Sentai Weapon options (single, double, unarmed) as a sentai ability, does Enhanced Weapon only apply to one of my Sentai Weapon choices or does it apply to all of my available Sentai Weapons?
Ex: Start with bow (single). Get pair of short swords (double) at 3rd level. Unarmed boosted at 5th level. Enhanced Weapon at 7th.