I have personally transitioned all these to stock DTHs. Functionality may be less on the stock DTH, but at least seems like the transition will be better. Then you might want to post in the community and hope that a developer will pick up your request for a driver, such as in this post here: Post Requests for Zwave Edge Drivers Here (community-created) - you might eventually end up with identical functionality.
I suggest that for these, you install the driver and test at least one of each type of your devices to ensure it works well for you. My understanding is that if you then leave the driver installed on the hub, and as long as that driver has the correct fingerprint for your devices, then during the “great transition” our devices will be assigned that specific driver.
I thhink you are correct - if these are cloud integration requiring no groovy DTH or SmartApp, then they should continue to work.
Not sure about this. I could never use Smart Lighting as it was not made available to European users (or was taken away, whatever the case may be). Groovy SmartApps will surely be killed off, and I saw that there will be a replacement for Smart Lighting, but could not see about anything else. I think the prudent approach would be for you to assume that they will die (including - with certainty - WebCoRE), and to create Routines as a replacement for the functionality offered by those SmartApps. I know from what I have seen that sometimes it’s not like for like, and I know from personal experience that the 200 limit is ridiculous and to replace a piston with these Routines will eat away at your allocation like crazy, but that’s what there is on offer at the moment.
You have to find the specific threads for the drivers you need in this community and follow the link. the developer will likely p[ublish a channel, then you enroll with that channel, see the available drivers on that channel and install it/them. As long as you follow what the developer says on the thread, you will get the latest version - when the developer releases new versions of that driver they will automatically be installed on your hub. Yes, it carries some risks which are detailed above in this thread if you care to read it all, but again - that’s what is currently on offer. Instead of the Groovy IDE you now have to install and use the Smartthings CLI. Of course, it’s a bit of a pain and not much of a UI at all and one hopes that there will be something developed to replace the IDE. But once again, just saying what I believe are the only choices for you right now.
Good luck!