1) Active/active mode is no longer recommended by F5, I wouldn't recommend it myself either. Is there a specific reason you want active/active?
2) Yes, it's just like SPAN.
3) You can use any TMM interface (or VLAN using a TMM interface) or (the mgmt interfaces (I think)) for network failover.
Relevant options should be under System > High Availability but I'm assuming you're not seeing that. System > Platform should have a High Availability option you can set to Redundant Pair which might make it appear.
System > License should let you know if your license is valid.
It would help if you could tell us what model the devices are and what software version please.