Interesting. Would you guys say that Gurmash has to pay 1 mana to cast the Battle Orders? You are correct that the wording on the Warlord is written in such a way as to suggest that only the Warlord is limited to once per round, but that same wording would also mean that he's the only one that would have to pay for them. As it doesn't say they cost 1 mana, just that the Warlord has to pay 1 in order to be able to cast them. I see no reason why one of these restrictions would apply to Gurmash and the other wouldn't.
I'm actually not sure which way is correct though. Do they both apply or does neither apply? I don't think I ever noticed or thought about it, and haven't had conversations (that I remember) regarding it. Being able to get the order repeatedly and for free would definitely be a big boost to having the familiar, but I'm very hesitant to accept that as the intention. As it is though, I see three possible interpretations here:
#1. He is simply triggering the Warlord's ability, and it is no different than if the Warlord had cast the spell. It still counts against the Warlord's limit and still costs 1 mana.
#2. He is copying the Warlord's ability and replaces the term "Warlord" with Gurmash". In which case he pays 1 mana and is prevented from casting it a 2nd time (via overextend or other shenanigans) himself, but the Mage could still cast it a 2nd time.
#3. He is casting the command spells without going through the ability at all. It doesn't cost him any mana and doesn't count against the Warlord's limit.
I don't think #2 is right, because I see no text to justify replacing "Warlord" with "Gurmash". But I do think this requires clarification.