If you sync from LRc then they are only smart previews and don't count towards your space allotment. Have you taken any with LR mobile? Have you let LR mobile sync with your mobile device photos? These both can take space in the Adobe cloud.
If you have Lightroom you already have this available to you. Check out this blog series. This is the first in a series of 5 https://www.lightroomqueen.com/share-web-gallery-lightroom-cloud/
Even a 35mm DX lens on a DX camera has the same field of view as a 52 on a FX camera. The 35mm is distance to focal plane it is not a measurement of the width of the lens. Some DX lenses will work on some FX cameras with very little vignetting.
If you do the math it is obvious that 1/600 sec is not fast enough. At a slow 15mph glide coming at you in 1/600 sec the bird will move 0.44 inches towards you. Plenty to induce a blur.
Does the bluetooth unit fit on the camera (Nikon Z7) if you have an L bracket on the camera or do you have to remove the short leg of the bracket to use it?
That depends on the L bracket I suppose. The attached picture shows it on the Z7ii with the Kirk L bracket which has a slot allowing it to make space.
There are multiple benefits to the 20gb subscription plan. If you import photos into Lightroom classic then sync a collection from there to the web only "Smart Previews" are synced and don't count against the space you have in the cloud. You can still work on them from any connected computer from the mobile LR or LR on the web and your adjustments will sync back to your LR Classic library.
Certain things won't work like direct connections to your financial institutions. You can still go to each site and download transactions to import though.