We can't give exact dimensions on the HS34 yet because I don't have them here at SnF, even though we do have production cases done. You're going to need to wait a bit until we can get that to you.
Here's the basic dimensions though: Exact same hight as a D100 product, 2" wide, not as deep as a D100 product. Now go cut your metal
Honestly, we hadn't considered that people would want to put it sideways, but we're now hearing that a lot from you and at the show. There's no technical reason it won't work sideways, but the writing will be rotated. Given all the feedback we're hearing, I think there's a good chance we'll be making one with the text printed on it "sideways".
As for radio support, we're not promising anything right now except 430/530 and SL-30 support. It's not that we don't expect it to work with most radios, but we haven't tested it everywhere yet. We should be able to support anything with ARINC or serial, but some of those may require future firmware updates. If the only connection the radio has is analog, that support will be fixed by our hardware, but we have done a lot of work to make sure it meets the standard.