I upgraded without problems to Lightroom Classic CC on my home desktop PC. Since that still runs Windows 7, I don't have the option to install the new Lightroom CC. However the 1 TB storage is attractive so I am pondering the upgrade anyway. I suppose I could install Lightroom CC on my Windows 10 laptop under the same licence. However I wouldn't want it to take up too much space on the SSD (photography is not the main purpose of my laptop!). Does anyone know if I could limit that somehow?
Yes you can, in several ways. First, LRCC needs space on the local hard drive (your SSD in this case) for it's catalog and previews cache. However, you can control the amount of available free space which LRCC can use by a slider in the Preferences>Local Storage setting. See attached:
Note also there's an option to store a local copy of ALL originals, which you would either keep unchecked or, maybe better still, allocate the location for the originals to an external drive as per my screenshot. It wouldn't matter if you subsequently started LRCC with that external drive attached, the app will tell you and will manage the situation intelligently until the drive is next connected.
Would LR Classic try to upload everything to the cloud or just the collections that are presently marked for upload to Lightroom Web/Mobile?
No. Assuming you've already got synced collections in your catalog, the upgrade process creates the upgraded catalog and takes over syncing duties from the old catalog. What was synced before will remain synced, nothing new will sync until you want it to.
Do I understand correctly that I could use Lightroom CC as "Lightroom Mobile for Windows 10" on my laptop? By this, I mean that I could import new RAW files from my cameras and process them while travelling. I would hope that there is no need to keep copies of them on the SSD after uploading to the cloud and back down to the PC running LR Classic at home. My full catalogue is about 400 GB at the moment and I definitely want to keep the images in their folder structure on the PC at home.
Yes, spot on. If you import direct from card, the originals are first copied to the SSD (or different location if you've specified it) pending upload. Once the upload is complete, those originals will be managed as per your preferences. If you've elected to keep ALL originals locally, then obviously they will stay. If you haven't, LRCC will keep originals and smart previews in accordance with the slider value you've set. If you need a picture to edit, and it's not held locally, there'll be a pause while the smart preview/original is downloaded. It's all a matter of getting it setup the way you want it, then let LRCC take care of it for you.
But if you first copy the new files to your SSD, then add them to LRCC, the app will NOT delete the first manual copy that you made, you'll need to do that yourself.
Presently, when I do this with Lightroom Web or Lightroom Mobile on my tablet or phone, the RAW files eventually land in dated folders on the LR Classic PC at home. Will that still happen?
Yes, if you just remember to check the Preferences>Lightroom CC tab in LR Classic to make sure the options to download to your specified location and folder structure are still checked following the catalog upgrade. They should be.
Hope I've covered everything, let me know if you need more info.