Even for downloading all photos from iCloud, the only option I see is to select the photos one at a time (the CTRL-click option).
So, enlighten me on how to bulk select all photos for download through the browser. I'm afraid, there's none.
That's why I shared the link to the tool that does the download job pretty satisfactorily.
But that said, I do agree that my response was not appropriate to the question of how to just "bulk select" the photos on iCloud.
I was more driven by the bulk-selection-followed-by-download need, and to that end, the tool I shared does an amazing job.
For the deletion part, one sub-optimal option (which still depends on the temporal distribution of the photos across months in a year) is to use the iPhone photos app, and do time-bucket wise selection bulk selection. But then that would make sense only if the photos are clustered temporally. If all the 1000 photos are taken, each on a different date, then we are out of luck. On the other hand if they have been taken over say 50 days, it's just 50 selections, followed by a delete.
And one photos are deleted from a device, we all know that they can be permanently "BULK" deleted (of course with bulk selection)