Is cross-platform play between Xbox One and 360 planned to be possible at launch? Can these players communicate with one another?

Yes, they want to unite the community. Cross platform play is to be a launch feature. And shit, I forgot to mention the launch window for the XB1 edition is by the end of the year. They really want voice chat to be available cross-platform as well. You will hopefully be able to play on the XB1 and talk to a teammate on the 360, but obviously parties won't work because they don't already work cross-platform.

I'm not going to speculate on cross-platform platoons, though. I'll ask about them instead and get a clearer answer.

Have they ever considered user created emblems or inscriptions a la War Thunder? Perhaps a fan competition to create them?

This one I won't ask because I think I can answer it. War Thunder is mostly played on PC where content creation is much easier. A personal emblem creator like, say, CoDBO had, is not worth the development effort for the return WG'd get from it. That, plus the fact that so many people think dicks are funny to put on their tank means that it could potentially raise the rating to M. That reminds me; the game has no visible crews so that it keeps the T rating, as opposed to showing the deaths of the crew which would fast-track it to being a game for a smaller audience.

OT: AFAIK there was an emblem competition at one point, but I may be totally wrong.

Are they interested in adding individual missions to Xbox, like they have on PC?

This one I'll ask. I want that T-55A!

It seems like the developers on PC are significantly more forthcoming with information

WG doesn't always share what's coming with WGA. As he specifically put it, usually he doesn't get to see what's coming out on PC until it's on the public test server. FtR actually just shut down, check the site!

So yeah, this isn't entirely intentional. WGA would probably like to be more transparent, but they usually haven't got enough information to actually share with us.