Using the cap

Kings accept.

I would pass on both of these. I think highly of olofsson, so the thought of adding a first and a second to him for mangiapane seems like an awful lot. I feel like for value, Monahan would need to come back and be a very productive middle 6 forward, just for the Sabres to break even. I think the Sabres are looking for more size for their d.

That's fair. I think getting roughly the same amount of goals but much, much better 5v5 play is worth it (even though VO has made a lot of progress in that regard). Could take the 2nd out, but I'm fine giving it up to get the deal done. Still have 3 1sts and 2nds next two years.
I'm happy with Monahan being a mentor for the 4 young centers we have, and hes there as a backup for Mittelstadt if he doesn't take strides next season, or gets you a 3rd for retaining 3 million.
I agree on your D point though, Walker is just serviceable and gotten on the cheap. I think he could play top 4 minutes if needed as well

Ryan Johnson going back to college, meaning is not gonna sign with Sabres, so may as well trade him for depth RD.
Sabres are giving way too much in Calgary deal. Knowing that Flames need to get rid of Monahan in order to resign their top liners, I would drop , Vegas 2nd, 1st from FLA (#32), give Sabres 2nd (#41) and that would be fair trade, depending how much money AM is gonna cost. VO is 4,5-5mil AVV and when healthy can be easily 25+ goals scorers.

Thanks for the feedback. I'm taking out the VGK 2nd, but keeping the 1st.

CGY still has ways to get under the cap giving away a couple picks to move Monahan/Lucic/etc while keeping AM, so I'm trying to make a fair trade instead of leaning too hard on the cap crunch.

Monahan comes in as another vet leader for free (not to the Pegulas, but I don't care about their bank account balance ). And Mangiapane has been one of the most reliable forwards defensively over the last 2-3 years while taking a major step in scoring. Similar goal scoring when VO is healthy, but IMO Mange is way more well rounded than VO even if AM goals regress a bit.