Essentially as I understabd it the B2 does not offer an in- built streaming abilty except Spotify which I refuse to use so have not tried it.
You can use the B2 to rip all your CD's in lossless FLAC format and play then either using the internal amplifier or an external analogue or digital amplifier.
You can control a B2 from your iPad or iPhone using the B2 Apple app or the web User Interface.
If you were to stream using either the iPad or iphone, then you could pair either apple device using Bluetooth with the B2 . The B2 would then play the bluetooth signal. This would not be the very best quality due to the limitations of Bluetooth, and that means the benefit of any lossless stream would not be retained . I find Bluetooth flaky at best and have only once used it with the B2. It wasn't worth it in my opinion.
The B2 only has analogue audio auxilary input for any kind of signal so again a lossless input would be degraded. I am not sure if the Bluetooth pathway is entirely digital or a mix of analogue
The B2 has a two options for digital audio outputs: Optical via TOSlink and HDMI so it can drive a high quality digital amplifier.
I hope this answersme of your questions.
Good luck!