I'd consider that a waste of space. The CIAs from 3DNUS take much less space, and have everything you need to return to an old version, should you want to. The 11.x series at this point only takes 6.5 GB. And that's with USA, EUR, and JPN versions (on both N3DS and O3DS). If I only grabbed one region and one hardware, it would be around 1.1 GB for all 7 releases. Still, it's your hard drive, not mine.
Well, they could do that in a future release. 3dbrew says that wasn't updated this time, however. The focus seems to be on playing outdated titles online (seems to be more to prevent online cheating by exploiting bugs in old versions of games than anything else, with a bit of preventing possible future online exploits on the side).
It does. There's no real reason to keep using A9LH, though. Everything that runs on A9LH also runs on B9S. I just keep it around for testing purposes at this point. But no NATIVVE_FIRM update means no CFW broken.