NewYearSRengo2002 B45 variation

The black cut  

Lucky: I think Black cannot cut with 1 when White plays the marked stone. :)

White descends (Black 10 connects)  

White 1 is the strongest answer. Black 10 connects.

White wins  

It seems to me that White wins.

Alternative to Black 4 above - outcome?  

I have not read it out completely, but if I did not oversee something early on, it looks like a complicated semeai, possibly leading to ko. But I'm sure I have overlooked something. Anyone?