I think I can help with some of this, my MC200 is full and so I have a growing collection on my TwinStore. I see it all on my Core control app seamlessly. This should be the same with QNAP.

I have everything backed up to an external drive for extra security of data. This is a MUST for the MC200 data at least.
If the house burns down, I will grab my external drive as I leave.
I don't want to re rip anytime soon.

For extra zones, get an MS200 which plugs into your network and gives full access to all your music without compromising quality, it will improve things in its zone. Sell squeezebox to help fund this.

Thoughts, Chris smile

No 18 in the Hall of fame smile I have simple tastes; I am content to settle for the best:
GIK monster bass panels, rear wall. QNAP TVS 471i3. Roon into DSP5200SE via 210/ 218 zone... Explorer 2. Bluesound Pulse 2, Mini & Flex. 596v1, 518, Foxsat HD, Sony BDP, Pioneer 5090, 2 Chromecast's for LRB videos. MS200 to F80 for a Roon zone