Can I get a brief rundown of possible companions? Name, race, class, alignment...

The main thing I wonder is what companions can do what in regards to changing class/alignment? What needs to be done to enable them to do such and what happens when it does?

Can any companion become a prestige class?

I'm the type of person who likes to do everything I possibly can then do it again but with a different alignment/gender/class combinaton. Knowing the information about companions ahead of time will save me many a reload/restart.

So... what can you tell me about the companions?

There's only one companion who can change class. The dwarf fighter. He can (your option) become a monk. He doesn't multi-class, he actually starts fresh as a level 1 monk and you level him up to 17 or so instantly. Otherwise, you can't multiclass anyone else (unless you download one of several mods that are out there from the player community).

Thanks, Fink.

What about changing alignments? I take it the dwarf will have to change alignments since he starts off at Neutral-Good. Is it possible to change Neeshka's alignment (or someones?).

Also, what are the companions?

I'm only in Chapter 2 but so far as I can see, you can't change alignments except when Khelgar the fighter adopts the monk class - he becomes lawful good from neutral good. When you level companions up, you are only given one choice of class which is their current class, that means no prestige classes either. Thus far, the companions who joins are (in chronological order):

Khelgar, male shield dwarf, fighter, neutral good (option to change to lawful good monk after completing his quests)
Neeshka, female tiefling, rogue, neutral
Elanee, female wood elf, druid, neutral good
Qara, female human, sorcerer, chaotic neutral
Grobnar, male rock gnome, bard, chaotic good
Casavir, male human, paladin, lawful good
Bishop, male human, ranger, chaotic evil
Shandra, female human, fighter, neutral good
Sand, male moon elf, wizard, lawful neutral

From what I gathered elsewhere, you can later get the following companions (may not be in the correct order):

Zhjaeve, female githzerai, cleric, lawful neutral
Construct, golem, fighter, neutral
Ammon Jerro, male human, warlock, neutral evil

Have fun! :)

Thanks for that, Ganz. Now I can play again without worrying about missing out on something serious.

Fingers crossed Obsidian will realise that the whole point of version 3.0-3.5 was multi-classed characters and start to play around with multi-classed companions. Oh well...