I did the mission, i didn't kill her, i just gave her away to that rapist. It took me less than 5minutes to re-do the mission because i got the red boyle(which literally walked down to the cellar and let me choke her out) and i gave her away.

Number two.
How can you make it through the canol barrier without getting spotted? I blinked under water and still got alerts.

Possessing a hagfish worked for me.

Takes 2 long to aim at those things b4 a tallboy spots you lol ill try it tho.

the tallboys are only scouting near the closing dam. you have virtually an unlimited time to aim at a hagfish I personnaly climbed back up to street level rather than go by the waters. I just blinked on top of those wooden log sticking out of the water and from there up to the streets. Happily, you aren't playing against the clock, so the barrier can very well close and you will be okay ( didn't even try and reach for it before it closes... Is it possible to pass under ? )

I went to the opposite side of the canol from the tallboys, blinked on top of the canol gate and jumped down. Didn't even get one alert meter on either of the tallboys.

I didn't walk out from the sewer canol, but instead I left the mansion from the top floor, and came down to Samuel from above. Much easier to see the tallboys then and avoid their vision.

As soon as I open the gate, I'm in the water, at the bottom and I blink across the canol so I'm against the wall, closest to the tallboys to avoid the spotlights. Then I blink my way to Samuel. I think out of six runs I got spotted once. I usually get nibbled by hagfish somewhere in there but it's not really a big problem.