Full spoilers.
The chair will always explode, if you miss the rolls you get some permanent debuffs (I've heard patches adjusted this, but I haven't been bothered to read those novelization of notes)
Telling the Dr you either still have the tadpole or have grown stronger will make her hostile, you can fight a small group of Githyanki but the rest of the Creche doesn't care. Telling the Dr you have amnesia or feel better defuses the situation.
If you want to bang Lae'Zel, you should put her in her place and demand you go first. She actually respects it, and it's one of the bigger reputation bumps you can get from her.
Telling
anyone
you have the artifact is a fight and makes you hostile to them all, fyi. If you want to romance SH you should keep it private.
These are extra spoilers so I'll block them out.
Siding with their "God", the General or the Inquisitor is how Lae'Zel's and the Gith plotline actually develops and are much more vague decisions you need to make, the chair is almost pointless. It's only plot relevance is to show you that the tadpole you have is extra, extra strength tylenol.
Since only from below can one better see the heights.
http://i.imgur.com/OhZgm.jpg