BeginnerExercise321/Attempts

No, no ko this way  

togo: ... rather here, and Black is dead, White alive.

Gote Seki -- in the event the Ko is completely unwinnable  

W wins 1 prisoner.

More seki  

togo: Also seki, also gote, also one prisoner. But looks more fancy! Aside from this, regarding , playing from outside is generally better; does not matter much here 'though, because playing until final position is pretty much forced. Positions and are miai.

B tenuki -- W 12 points?  

Is it possible to outright kill, or seki in sente?

togo: What about other White plays after Black tenuki?

Seki in sente  

edmundangles: But sadly not sente in both variations.

togo: Unfortunatedly this is not seki, Black is dead here (and White alive).

Not sente  

edmundangles: But sadly not sente in both variations.

togo: Unfortunatedly this is not seki, Black is dead here (and White alive).