Does support work better if both units have the same element?

What other parameter affect the support bonus?

 Look here: http://serenesforest.net/fe10/support.html

I think that should explain it.

You don't need any of this though - I finished the game on Normal without knowing anything about Biorythms, supports, the weapon triangle and very little about terrain bonuses.

On hard though - you'll need all this.

Aran i felt was quite good, in my 2nd runthrough of the game. Him, Nolan, Tauroneo, and Zihark became the supporting pillars of the Dawn Brigade after i took Jill away from them (because i love Jill, and wanted to see her reach her full potential, which could only come through Greil Mercenary membership). The Soldier-Halberdier-Sentinel class really ranked up from Path of Radiance, where they were fairly useless. Aran became the glory of the Dawn Brigade, and Nephenee became the heart of the Greil Mercenaries

Nephenee is one of the best long-term investments in the game. She starts out pretty bad, and will need babying throughout Book 2, but throughout book 3 and 4 she can become a frontline character of sheer pwnage.

Aran is so-so.  He has 3 problems.

1)  Low resistance.  Not surprising for his class type but at 20/20/20 he's sitting around 20 resistance while Nephenee is sitting at 30.  That's a HUGE difference.

2)  Lances + Low speed.  Lances do less damage than axes and without a high speed, he can't double often enough to get 1 turn KOs as often as you'd like.

3)  Low luck.  Because he'll probably be trading attacks with enemies (unless he always has a partner or two), this might hurt over time.

He has a few things going for him though.  He does well in Attack and Defense as well as having an element that gives +2.5 Avoid per support level (making up for his low luck in some cases).

As for Nephenee, she can be amazing.  You need to get very RNG blessed with her Strength stat though.  Otherwise she's not so great. >.>

http://serenesforest.net/general/misconception.html

So, Iron or Steel weapon, what matter is how often you attack, not what weapon you weild.

At the begining to Book 2, when Haar appears, do I have to talk to him to get him to join up?

I already passed that chapter without talking to him, let me know if I should restart at that chapter :)

Yes.  You must have Marcia speak with Haar in the Part 2 Prologue.

Woah, end game so fast with the second part. Only 4 chapters?

Really, you're not halfway yeat. Book 3 and 4 is where it gets reaslly interesting.

A small hint (something I messed up): You CAN kill main characters as long as you're not playing with them (as in: they are your enemy in a chapter). I did anything to avoid those, which migh explain my insane amount of BEXP, but it did make the chapters very tough.

Part 2 was disappointingly short.

Part 3 is roughly 3 times as long as Part 2 though so there's a lot to go.