Mac newbie needs advice on initial setup with NAS

First post. After 30 years with MS, and 20 years as a professional developer on the Windows platform, I've finally had enough.

I have a new 27" iMac 5k with the 1TB SSD coming next week, and a Synology NAS to go with. The intent is to use the SSD as a "working" drive, and keep the bulk of photos, music, and videos on the NAS, as well as using the NAS for backups.

My impression is that the native Mac apps for dealing with media files tend to want to manage the files themselves and put them where they want, on the root drive. I realize that as a newbie I should try and go with the flow, and try and adopt the Zen of Apple - but the SSD won't come close to holding my files, and I don't want to have some terrible time unsorting a mess.

I would also prefer to keep the bulk of my personal files on the NAS if possible.

If I am mistaken in my impressions, great, please let me know. If not, some advice on how to approach this so I don't have to do it over 3 or 4 times would be appreciated.

If you are using iTunes, the iTunes directory can be specified in any location you want. I don't have a reference at the moment but a quick Google search should find it.

I use Photoshop and Lightroom to manage my photos and can easily specify locations on external drives. Likewise I am using Final Cut Pro X for making videos and Plex for a video library and specifying storage locations is a snap.

I use the stock Apple Photos and iCloud Photo Library to manage my images. I am just a hobby photographer so my needs are light and I like the syncing between all my devices. The editing tools are good with Photos (better on the Mac in OS X than in iOS) and I use Affinity Photo on the Mac if I need to edit images with more power. I think Photos allows for two methods of storing images: managed, meaning it takes care of everything for the user in a managed Library or referenced, meaning you can manually manage your images in a Windows-like folder system. I stepped back and let Photos do the managed approach for me. Read up about this before you start. I think you can keep either on an external drive, but it takes some planning.