Late comment is late, but...
I have to say your idea is very interesting. From the previous versions, the main feature of Imladris was that its soldiers need no experience, as they have trained in martial arts for centuries, and so are pretty much the strongest base combat units. I don't know if that will be changed, but the concept was perfect.
So, given their ability to fight, it would make sense for them to be able to fight mixed together, spearmen defending their archer companions and so on, as the feature was already present in mages, so it's not out of place. And one would imagine that being few in numbers and training for so long, they got used at working all together. This is a feature that would indeed differentiate Imladris even more from all other factions.
On the music, I wouldn't know, as it currently is very implemented in Lothorien, and while Galadriel has her Chanteuses, Imladris's special units are the Scholars, whose deep immersion in the studies of various arts give the faction all the power it needs. While it would be an interesting concept, I don't really see Rivendell's musicians running to the battlefield with heavily-armored troops (unless they look like this
http://images2.wikia.nocookie.net/__cb20101004125356/saintseiya/images/b/bb/Silver_-_Lyra_Orphee.jpg XD ), and that would be kinda too similar to Lothlorien. I admit I would like to see the music implemented, but also Imladris has the Song of Luthien as a music-related spell, so I really wouldn't know.
Perhaps the musicians could be part of an extension of the fortress (like in previous versions there were the mages atop towers) that give it extra defense slowing and debuffing enemy units. That is IF there will be any fortress extension, as there could be other options for such buildings: a Sacred Fountain (sacrileged by Dwarves XD) to heal closeby units, Resting Areas (more CP), and so on. I'm just throwing concepts out there here, but I hope you get what I mean.
And I agree on the CaH thing of having armored units. Well, even having melee Elves wouldn't be so bad