This could be a spoiler if you don't know yo ucan do it...

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The trang and umpani. If I do all but the last quests of each group, and pay of He'Li. What else and when do I do what to get them to join up? I'm 2 quests into each group. Z'Ant even expressed his wish to eventually join together against the true enemy, the Dark Savant.

There is a Rapax encampment (it's in one of the wilderness areas either the southern or mountain) where an Umpani and a T'rang are being held prisoner. Rescue them and they'll tell you their plans of getting their leaders to ally. DO NOT complete the final quests for either side btw or the alliance doesn't work. (ie do not destroy umpani mothership or cause the t'rang birthrate to decline.)

ALso, I find I have to do most of the T'Rang quests first or they stay mad. At one point, I always try to get to the T'Rang transporter. Unfortunately, I have to kill an Assassin and Overseer, or whatever. In some games the T'Rang forgive me, others they never do. Even if I have done 3 or 4 quests for them (all but the last). I wonder what the story is here. It may be related to leaving nearby survivors from the battle, but I kill all in the room. Do they communicate with others (if I use Pandemonium, for example, and they flee.). Is it random? Is there a trick? It makes me want to wait much later to try to get to the transporter, I guess through the mines, but that takes much more time...

Each creature you kill of a given faction reduces the whole races disposition by one level. So if the are friendly killing the first one makes them neutral. Killing the second one makes them hostile. Once they are hostile they will always be hostile.

For the Trang just go through the mines. It is not really that difficult and they are some decent items in the section of Martin's bluff you get to. Another option I have heard is to run through the section to the transporter. If you never kill anything, eventually the battle will end and you will not have any problems.

The trick to accessing the trangaporter the first time it to enter the room with the assasin and overseer, approach just close enough to get the loot out of the corner, move back accross the room to be nearer the door [without the assasin getting hostile] then initate combat, but RUN past him, through the door he's guarding, and down the hall rather than fight.

If you get far enough down the hall that all characters are out of range, combat automatically ends, and since you haven't killed or even attacked anyone, the trang stay neutral. DON'T cast any spells like hypnotic or sonic boom-- those are hostile acts.

Be sure to open the iron door to upper Martin's in the right hand stair, set a portal if you have one [this is the single most useful portal spot in the game, by far: 4 destinations for the price of one], and go up the left stairs, fight the ghosts, go down the further stair to the 'back area' of LMB, and open the hidden door near Z'ant for future use.

IF you've left both these doors open, you need never walk through the assain's room again, though if for some reason you choose to, the 'run' trick works every time, from both directions.

Just save before you do it, in case you start at the wrong spot or don't run far enough.

HTH
Oru