F5 LTM pair software upgrade - 11.4.1 to 11.6.1

Question 1: Yes

Question 2: Yes (assuming you then go and upgrade Device 1,)

You've suggested a wholly sensible approach to upgrading. Couple of tips. When you've re licensed the device, go to cli (Bash) and issue a reloadlic , then a tmsh save sys config. If you've never done it, test traffic on Device 2 before the upgrade. Schedule this upgrade in an agreed maintenance window. DISABLE VLAN FAILSAFE/Other Failsafes that are applicable. Have connectivity to an AOM interface, or via a Terminal Server/Phsyical Laptop connection. The "Moving" of the traffic assumes that the switches you're connecting to respond to gratuitous ARP requests, should be if they're enterprise level.