Each extra attack takes a -5 for weapon attacks.
Arktos can use all three of his actions for the round to make all of his natural attacks at their normal rolls.
Grapple will provoke an AoO unless you have Improved Grapple feat
Quote:
Initiate a Grapple (Attack; 2 Acts): You initiate a grapple against a creature within your melee reach.
Continue a Grapple (2 Acts): You continue a grapple. If you initiated the grapple, you must either take this action at the start of each subsequent turn or end the grapple as a free action. When you take this action, you attempt a grapple combat maneuver check with a +5 bonus. If you're successful, you can either move, deal damage to, or pin the creature you are grappling. Alternatively, you can attempt to tie up the creature with a rope.
Tie Up a Grappled or Pinned Creature: If you have a rope in your hands, and you are grappling or pinning a foe, you can attempt a grapple combat maneuver check at a –10 penalty to tie up that foe. If you're successful, the ropes pin the creature until they are removed or the pinned foe succeeds at a combat maneuver check or Escape Artist check (DC = 20 + your CMB).