His BAB is + 7 / + 2, adding his strength bonus (+4) to + 11 / + 6, taking -2 second level attack power (+4 damage, -2 touch), the character should be seated at + 9 / + 4 (1d6 + 8) when using only his main hand to attack, and + 7 / + 2 / + 2 (1d6 + 8, 1d6 + 8 and 1d6 + 6) when using both hands to attack.
For the main hand, the damage is +8 (4 of the force 4 of the power attack)
Assuming he has not yet studied his target, yes. What he should, because he adds an apartment +2 at attack and damage against his target, for a total of +10 damage, and all that it costs is a Quick action at the 7th level.
and for out-of-hand damage is +6 (4 of force 2 of the power attack).
Yes, because of the double slice. Again, against a target studied, this should cause +8 damage.
Everything about Power Attack is correct.