Hanfin will surely garner a nice package.

But he will not get Robertson, Niemela and a 1st. Let alone add Timmins and Hirvonen.

Robertson is a B+ forward prospect
Niemela is an A- RD prospect
Timmins has limited value but some for sure
Hirvonen is a C+ forward prospect

Anyways we should not be spending all this for a pending UFA. An extension would need to be in place.

I would do Niemela + 1st + Hirvonen(or a 3rd) for Hanifin extended 6.5m x 8 years. Otherwise no thanks.

That Carolina deal makes sense for both teams. I would try for Jarvis over Necas but either way it works.

Overall I like the trades and the team you put together. Consider the following.
1) A cheaper option than Pesce would be to target Tavev from Calgary. They are very similar players (both excellent defenders, that skate and move the puck well and are not very physical). The price for Tavev would be less, but they play a very similar game. Pesce is younger and better (..but not that much better).
2) While the Defense you proposed is highly skilled, they still lack size and physical play to clear the front of the net. Unfortunately Graves, Mayfield, Schenn and Soucy have all signed. Zadorov is another player in Calgary that would fit the bill here. If Hanifin does not want to play in Canada, then the Leafs would be foolish to pay such a high price for him if he won't resign.