Andrae and Attard both should get NHL time to see if they can stick and keep developing.
Besides Andrae & Attard, you have York, Drysdale and Zamula that need to continue to play and be evaluated/developed.
And have Sanheim and Risto signed long term with likely unmovable contracts.
Staal should definitely be moved for whatever is offered. He is not playing, he is here for "vet depth" and, as we know, it is hard to lead from the bench.
Walker has played well, d-men have value at the deadline especially with his experience. Ask for a 1st, absolutely, try to maximize the asset. Settle for a 2nd and/or another player who fits and go from there. Walker should be moved.
Seeler is the one that Torts and the FO seem to love the most and thus will be the truest test of their commitment to the rebuild. He is cheap and plays hard. If they want to extend him for 1 year or max 2 years at a cheap rate, I would not love it, but it would also not be the end of the world. I'd rather move him for what you can get now which I think is probably his peak.