Yeah, it'll have Linux support. We're using Unity (a graphics middleware) for the client, which can build for Linux. In fact I had a Linux client for a bit, but the Unity support was too buggy, it was just a big hassle. Fortunately the new update of Unity improves Linux support... but it breaks some other things. So probably the
next version of Unity, our middleware will be in a good place for it and we'll start releasing Linux builds.
On Steam... yeah, probably... should probably look into that, huh?

I wanted to get the game a bit prettier before I tried that, since Steam is so graphics-sensitive. But yeah it's something I'd like to attempt soonish.