Phalanx soldier build and question on TWF & AoO's

[LuxuriantOak]

So I'm playing a game next week in a pf-eberron setting.
We're starting at lvl 5; I've made a phalanx soldier 3 / urban ranger 2.
It's a trip-build; combat expertise, improved trip, combat reflexes, improved shield bash.

why I'm dipping ranger:

If you're wondering, I'm multiclassing to ranger because I prefer the skill ranks, class skills, ability to use CLW-wands and the other ranger wands, & the other class abilities from the ranger class.
The original build was pure fighter 5, but I realized that the ranger dip doesn't lose any feats because of the fighting style feat.
I also don't consider the lvl 5 phalanx ability that important since I'm not that focused on damage - another player has a 2handed warforged barbarian to deal with the dpr-olympics :)
In addition I'm aiming for the Blade of Orien prc next lvl. (A teleporting warrior-type) -so none of the class abilities will scale beyond where they are at lvl 5 ...

I'm suddenly wondering if I need two-weapon-fighting?

The plan is to use a guisarme-glaive for AoO and tripping, and a spiked shield for enemies that get past and adjacent.

So how does it work?

Ex:
1 round - I stab an enemy with my polearm.
On the enemy turn he moves adjacent (not with a 5ft. Step to keep this simple) he eats an AoO for that.
2 round - I shield bash the enemy (or use bull rush to move him away)
On the enemy turn either he or another enemy provokes a (reach) AoO, I stab with the polearm.

-is the AoO a TWF-attack since it is in the same round, and I'm using a different weapon than what I used for my attack?
-do I apply twf-penalties retroactively to the shield?!
-is there a scenario where I will get twf-penalties using these tactics?

I'm pretty sure the answer to the first 2 questions is "nope", but I want to be sure.
I'm also thinking to get the bodyguard feat later and use it with the same setup (polarm-and-shield)

If this is a silly question I apologize, I'm just double-checking things before the game to make play run smoothly. Dotting my "i"'s and such.

[Eltacolibre]

Single attack = no penalties. You will only get the penalty if you decide to attack with both at the same time.

[Rodinia]

There is no scenario where you will be forced to take TWF penalties, unless you bring it on yourself. You are totally fine unless you are silly enough to try to attack with both polearm and shield during your turn. TWF is a trap, although I suppose one weapon having reach makes it less bad.

AoOs are always made with your best attack, and don't hinder you in any way.

It's great to be able to use both shield and polearm. That defensive stance will likely be your default. For your offensive stance you presumably put the shield on your back and hold the polearm in two hands. Perhaps work out the relative damage, difference in AC, and use that to determine which stance to be in. STR and Power Attack damage bonus will both be x 1.5 instead of x 1.0. It will probably be about -3 on AC for about +4 damage, so probably only worth it when in total offense mode.

You need not be overly concerned about threatening adjacent. Reach alone is usually sufficient. If you care about it, wearing 10 pounds of 50 gp spiked armor does the job, as does the Improved Unarmed Strike feat. Shield spikes work, too, except when you drop your shield.

[lemeres]

You only need TWF if you are using both weapons during the same full attack.

Honestly, if you are using a reach weapon, it is actually kind of hard to get both the shield and spear to attack on the same guy at the same time (it mostly requires a large+ creature getting right up on you..and many of those do not need to do that, since they usually have a large enough natural reach that they do not need to).

Overall, the spear shield combo is fine, and lets you deal with tricky casters and such.

Oh, and because I always advocate this- Lunge at level 6/7 is great for reach builds. It doesn't increase your threatened area for AoO's (since it ends when your turn ends), but it lets you position them more effectively. This is because it lets you end your turn with the enemy 15' away, rather than 10' away. This means they many can't just take a 5' step to get to you, and thus they have to draw an AoO. Lunge also lets you full attack anything in a 45' circle with your reach weapon...which is always nice.

[LuxuriantOak]

That was what I thought, thanks for all the replies.
Now I thinking I might ditch Improved shield bash for something more useful like lunge or bodyguard... I guess I'll mull it over untill we play :)