I know that you can get one ring of wizardy from the stronghold, but I heard there is a 2nd one somewhere in the docks district. Anyone know if this is true or how you get the second ring?

If I remember correctly I had 2 rings of wizardry once myself but I don't know where I got them.

Spoilers
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1) Loot off one of Galvary's mages in one of Jaheira's Harper quests.

2) Reward from Planar Sphere stronghold, requires the death of one of your apprentices though.

hmmm so I guess that means I need jahiera. I hope she will join me now since I told her to bug off in Irenicus' dungeon. How do I start the harper quests with her anyways?

You go to the harper hold do a quest for them, and then the guy outside who ants his buddy and then your in, i think they fight you in the hold and then they randomly try to get jaheira dead, so you kill them, unless ur in the romance with her then you can avoid the violence one time...
Felix

SPOILER
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When randomly traveling, you will be "waylaid by enemies" sometime in the game.. I don't know what triggers the quest, but you probably need to be in Chapter Three.
You will find a few thugs and a man lying on the ground, and the thugs will attack you, telling each other there must be no witnesses.
After winning the battle, the man on the ground will tell you he's poisoned and asks you to take him to Rylock in the Docks District. Take him there.. it's marked "Galvarey Estate" on your map.
When you go to leave, you will find none other than Xzar, standing near the Sea's Bounty. He will ask you to help him. And so the quest begins.

I already did the quest with the poisoned man, and the quest for Xzar while Jahiera wasn't in the party. Where do I go from there?

No, it can happen in Chapter Two.

You need Jaheria in the party for it to go any farther. She'll start whining about how she needs to go to the Harper place for a while, then come and whine about how you need to go there so they can attack you, and so on.

Also.... I noticed in an item browser that there is a true dead Montaron. Is it possible to find his true form instead of that Harper bird or is it just some fluke item? And if so, where is it?

Sorry, you can only find Monty's body after Xzar is killed and if you get into the Harper Hold again with Jahiera (and confront Galvarey.) It's spawned in an upstairs treasure chest.