can photos be deleted from iphone if they are saved on iclou

The short answer, yes.

If iCloud Photo is turned on, on your iPhone, then your photos sync automatically with iCloud. If you have a photo on your iPhone and you delete it, then the syncing starts and the photo will also be removed from iCloud.

If you have deleted an image, you can restore it in the Recently Deleted folder.

If it is deleted from that folder as well, then the image is lost.

You can read more about iCloud Photo here:

https://support.apple.com/en-us/HT204264

No. If you delete a photo in icloud, it will delete from your connected device (and vice versa).