I've seen these three players sent to the Caps a lot. Like A LOT.

Let me start off with saying Kampf is a no go. Even if it's just to make money work, that contract is awful, and the Caps have Dowd, Sgarbossa, and Malenstyn all as really good 4C options. Kampf doesn't crack next years opening roster. Also I don't know where y'all get the idea that you'll get picks for Kampf. Nobody is paying for that contract.
I'd love Robertson on the Caps. I'd give a 25 2nd for him, nothing more. The Caps have Miroshnichenko, McMichael, Lapierre, Malenstyn, and Protas in full time slots already with guys like Leonard, Cristall, Suzdalev, Dube, and Sutter pushing in the next couple years. So giving up premium assets for a young winger isn't an absolute priority.
Same with Liljegren, I'd give up a second next year. I really like him as well, but we have 3 RD locked up for 2 more years, with Iorio on the brink of an NHL spot and Chesley pushing in the next few years. RD is probably the least of the Caps worries.

Also I've seen Jensen half retained going back to Toronto. I'd do that straight up for Liljegren, that's about it. Jensen on his own is worth probably a 3rd, with half retention for two years, it'll be closer to a second, maybe a little more.

Sandin and Fehervary aren't moving so you can forget that.

You may have Ethan Bear for free.

Hope this helps!