Disklavier

Hello group,
I bought a Yamaha baby grand (one size up from smallest) in 2008. I upgraded to a DKC-850 control unit a few years ago.
1). Can I use my Yamaha as a "silent piano?" so that I can listen (through headphones) and not disturb others in my household? We couldn't find a headphone jack on the piano...if needed I can send a photo of my piano
2). I have a midi-interface that I'd like to hook up to a computer and use Logix. I read my new manual and there are many sounds I appear to be able to key in (and I assume, record) to bring in other instruments besides piano. Does that mean my piano keyboard is basically a midi controller? Can my keyboard also be used to key in sounds pre-loaded from Pro-tools or Logix?
3). If I play the piano and record it on the Disklavier, then transfer the file for editing and quanitzing through my midi interface, does that mean I then have a "recorded" file in my Logix or whatever computer software I use? (In the past I transferred piano tracks through a flash drive/USB connection and then edited them on the computer, then put the flash drive back in to "playback" my edited recording and used a mic held above the piano to record the player piano as if it were live...and am wondering if that's not necessary!)
4). My new iphone has "garage band" already loaded on to it...is my DKC-850 compatible with the Apple iphone? Could I plug my iPhone USB jack into the USB jack on my Dislavier and use Garage Band?  In fact....are there any headphones that have USB jacks I could plug in to the piano and make it a "silent" piano also?
Thanks- if you could do me a favor-  if you respond, put your answers to each question you know the answer to, underneath each question. That way we'll be less confused....or at least I won't get confused...
Thanks to all for any help you can provide!