Yep, as has been said, keep moving until you find them. It will take a lot more snow to push bulls down than it will cows, but there are bulls that will stay low all year and some will stay high. It's not like every elk is going to be at the same elevation in a unit.
Yes, in general you have a morning and evening glassing spot. If those don't work out, move to new spots the next day. Keep moving until you find them. Sure, they can move into an area you were already at, but it's better IMO to keep moving and trying to find them instead of staying in the same...
With it being the 3rd week, the bulls not coming into bugles could be because they are smaller bulls that have gotten beat up over the last few weeks and are timid, or it could also be that the bull wasn't going to leave his herd to go chase you down because you weren't close enough. Either one...