You are taking a walk through the woods without a elk call.
A elk call might not work on public land. On private property especially if you dont know the land to well, A cow call is a must have.
But I am also a fan of the spot n stalk method. It just depends on the elk and the terrain.
Ps. dont mess with the bugle. Get a cow call.

Gen is right although getting a bull to bugle back is one of the best experiences you will ever have!
All of the points you made are good.