Newbie question about Vault 2i


I am about to order my new home theater and I am planning on buying Vault2.  I have Ethernet set up in closet where the gear is. 
I am planning on converting my CD’s and also signing on to either Tidal or Qobuz.  
The way I understand it is whatever music I download will be stored on Vault until I drop service.
Vault will be connected to my new receiver.
I will access the music via my iPhone and iPad, correct?
will a subscription to Roon make it easier to use Vault or is the software easy enough to use. What is the Value of using Roon?
Would converting to FLAC be the best option. 
Is connecting to receiver via rca cables to analog out the best way to go
if I didn’t care about converting CD’s would Node 2i be a good option for a lot less money? Is there an advantage to storing Tidal files and Qobuz on on Vault rather than just streaming Tidal to Node 2i.
thanks 
Bob

galleybob
I was all set for Vault 2 but after considering all the money I will be spending on Home Theater I think I will just spend $500 on Node 2i. My reasoning is that I can live with the conversions of my CD's to AIFF that I have done. Unless I am missing something I don't see why I need HD of Vault as I won't be purchasing music. I think for streaming Qobuz, the Node2i will be fine. I may be wrong on this. I know Tim said I have to store music somewhere but my nephew who uses Tidal said streaming is not a problem and he does not store the music on HD. As far as my converted Aiff files they are now in my iTunes folder. Wouldn't the Node 2i be able to access this.
I don't have any plan as of now of adding Roon. Thanks
@galleybob - If your AIFF files are on a system that is attached to the same network as the Node2i, the Node should find them. I don't own one, but I own another streamer and that is how it works. It will catalog every audio file it finds on the network.

Hopefully a Node 2/2i owner will chime in and validate my assumption.
I bought the Node 2i and set have it hooked to my receiver via analog. I am listening to Tidal MQA files. I have also set up a Network HD for my AIFF files which I converted with my Apple Superdrive. The files sound pretty good for sure but I think Tidal MQA is better. Would the Vault 2i do a better job in converting my CD's and would my CD files sound more like Tidal MQA. Thanks