harpoon+greater grapple?

[truesidekick]

using the feat Hamatula Strike, i can auto grapple someone with a harpoon if i choose to. once grappled the feat allows me to either move or "make an attack action" to damage the person.

here is my question, would greater grapple allow the attack action to function as a move equivilent, after maintaining the grapple? and then would i be able to use rapid grapple to get a swift extra attack action?

here are the 2 feats

Spoiler:

Hamatula Strike (Combat)
You can catch your opponents on your weapon and hold them in place.

Paizo Peripheral

This content is from Paizo, however it is not part of the Pathfinder Core Rules.
See here for details.

Prerequisites: Improved Grapple, Strength 13, Base Attack Bonus +7.

Benefit: Whenever you damage an opponent with a piercing weapon, you can immediately make a grapple check; success means the opponent is impaled on your weapon and you both gain the grappled condition. While the opponent is impaled, as an attack action you may make a grapple check on your turn at a -4 penalty to damage the opponent with your weapon, even if your weapon cannot normally be used in a grapple.

Normal: You can only attack with an unarmed strike, natural weapon, or light weapon against opponents you are grappling.

and

Spoiler:

Greater Grapple (Combat)
Maintaining a grapple is second nature to you.

Prerequisites: Improved Grapple, Improved Unarmed Strike, base attack bonus +6, Dex 13.

Benefit: You receive a +2 bonus on checks made to grapple a foe. This bonus stacks with the bonus granted by Improved Grapple. Once you have grappled a creature, maintaining the grapple is a move action. This feat allows you to make two grapple checks each round (to move, harm, or pin your opponent), but you are not required to make two checks. You only need to succeed at one of these checks to maintain the grapple.

Normal: Maintaining a grapple is a standard action.

now if the attack action stays as a standard action, would i still get my 2 extra grapple actions to pin then tie up the target? and then would making that pin allow for pinning rend and other pinning based feats using the harpoon as my weapon, seeing as though the feat makes it available to use in a grapple?