A) Faramir calls a Heroic Move (and With Me!), and Erkenbrand an Heroic March (and At the Double!). Farimir moves first, his mount moving 10". Next, Erkenbrand then puts his March in action so he and all his Rohan Riders move their 15". All end within 6" of both heroes. All good and legal?

B) Heroic March specifically mentions 'mounts' as being able to move an additional 5" instead of just 3" for foot models. So Bat Swarms would get an additional 3" (as a 'foot model'?) but a Fell Beast would get an additonal 5" as a mount? Is this correct?

thanks

A) this is how I'd play it. Remember that you cannot charge if you use Heroic March...

B) in the official FAQ (Hobbit Unexpected Hope, V1.2 in french), there is an answer to this question : only mounts (including monstruous mounts) add 5"

Hope it helps