1) The game's version is 1.023 (1765) (Final) Aug 17 2009, aka the latest version. There's no need to patch it manually.

3) GOG also provides serial numbers for online play. I haven't tried that myself, but it should work.

What "gamebreaking bugs" have you read about everywhere? The worst bugs I recall with NWN2 involved cutscenes not firing, which CAN be gamebreaking if someone doesn't save their game regularly. Otherwise, I don't recall having any issues with the game.

The NWN1 last patch needs to be reapplied to fix some character creation bugs no need to apply the last NWN2 Patch tho. As said previously GOG supplies Serial keys for Multiplayer and for those wanting to do LAN plan its easy enough to have one game use the generic keys that come installed and the other player to use the keys on their accout if you are wanting to do 2 player LAN that is any more people and they will be needed their own Copies other wise you end up getting an error stating that the keys were the same and you wont be able to play.

Well the watchman quest is Very buggy, in 4 attemps I have only got right through to Blakelake once.
You journal tells you to report back to Marschel Cormack or the captian & they don't know you have completed the previous quest. So the game is broken & can't be advanced.

The one time I got through to Act II, I had a bug which stopped Neeska from following the group, so if I needed her in the group I had to lead with her.
So I start another new game & made myself a rogue so I wouldn't need her & now I'm back to Captin Brelaina to report on saving the emissary & the dialogue option is not there.
Maybe someone could make a mod that tells the NPC's to just read the journal.

So if the OP does buy the game maybe just avoid the original campaign.
I'm hoping one of the others is more playable.

I wasn't doubting that such bugs existed, but I didn't encounter anything near that degree of difficulty making it through the OC. I had some issues with cutscenes not firing in the final act, but otherwise, I had a smooth run. I might have been lucky, or maybe some paths are less buggy than others.

The original release was a mess. There were a LOT of game breaking bugs, but the vast majority were fixed in the first patch. The rest were fixed piecemeal over time. I guess there are still some issues beating the Watchman quest, but personally I've never had any problems with it.

The NPC AI does crap out from time to time, but that can be fixed by toggling the AI off and on.

Olnorton, are you using the voice commands? If a character isn't following you, then use the voice command "Follow me" (or "Attack"). (Voice commands are accessed by hitting the V key.)