Very sound decision starting out with the Bluesound Node to get yourself acquainted with streaming music. They make a solid product and are well established.
I used a Node 2i for a number of years and was never dissatisfied with its sound quality and streaming ability just using the original power supply. I did move to an outboard DAC in time but the onboard DAC was decent and enjoyable. You can also disable the volume control in the Node as you suggested.
Be sure to go with the newest version of the Node as I believe they have upgraded the DAC design and possibly some other features.
Enjoy the music! That’s what it is all about!