When setting up HSRP does the VLAN number make a difference? I would assume all the outgoing interfaces would need to be a part of the same VLAN. Based on the videos it seems to be standard that most of the interfaces be moved out of the default VLAN for security purposes, so if using VLAN1 like in the videos do you just leave the outgoing interfaces on the edge routers in that VLAN, then set up routing between the VLANs?
HSRP and VLANs
The ports do need to be in the same vlans to generate that Virtualized Gateway IP address. If they're in different IP subnets, then it's not possible to do create that virtualized gateway.
Usually, that's why you tend to do FHR (First Hop Redundancy). is because you're trying to provide that redundancy for your gateway. You can do inter-vlan routing between your vlans internally.