OK, I've been lazy in answering but here it is -
1. Use Roon - Yes
2. Lifetime - went directly from a 60 day free trial to lifetime...and glad I did since they raised the price!
3. Roon core-server is a sonicTransporter i5-CDR with 2TB hard drive. Multiple playback devices - main one is the Trinnov Altitude 16 which is Roon-ready. The other playback devices (designated as zones) are 4 laptops which have Roon playback software installed. For the Altitude, I use an ipad for the Roon playback app. I also have 1 other playback device: a Sonore ultraRendu Roon-ready player connected by USB to an iFi Pro DSD DAC for headphone and analog stereo tube preamp. The sonicTransporter, Trinnov, laptops, & Sonore are all connected by wired ethernet.
4. Western Digital mycloud 4 bay NAS used for backup of music files only, not playback. All playback music files are stored on the sonicTransporter.
5. NA
6. Only other music software I've ever used in itunes & that was only to get music onto the phone and very occasional PC playback. I know...a no-contest comparison

. I've tire-kicked J River a few times, even to download a free trial once but never was that interested in computer file based music until I bought the Trinnov Altitude. I was married to discs. The Altitude being Roon-ready was a big factor in changing my mind as well as a very persuasive Trinnov owner (audioguy) that I've gotten to know well.
I initially used Roon for my local stored files purchased from various sources: Acoustic Sounds, NativeDSD, Qobuz & even my itunes aac files. I finally signed up with Qobuz recently since they announced their big price reduction and streaming only hi-rez & CD quality. Went with the annual subscription. If they ever offer a lifetime option, I'd probably go for it.
On my impressions of using Roon & Qobuz & what it's meant to my decade's of music listening - wow! I've even setup a few internet radio stations in Roon that I occasionally enjoyed using the Marantz prepro and Pioneer AVR. It's all there in 1 package.