iCloud photos

I have photos on my hard drives and I’d like to check them out and review them manually on my iPhone. And also sync those which I may need.

For that I am planning to buy a bigger iCloud space.

Once I purchase more space I’ll connect my external drive to the Mac. Import photos and then put them on the cloud.

From there I’d review them on my phone.

Now, my question is -

Would I be able to delete photos from my phone as well as iCloud in one go to would I have to do them separately ? Since I am anticipating there would be a huge number of photos/videos that have been duplicated ( earlier on windows machines ).

After doing this, and the edits I’d prefer removing old pics from the cloud once.

When I delete a photo from the phone, would it be deleted from iCloud as well ? Because I’d like keep my phone memory as free as possible.