iPhone photos

iCloud Photos is a syncing service. Any photo you delete from a device where iCloud Photos is turned on will also be deleted from iCloud and from any other device connected to iCloud Photos. You can potentially reduce the storage space required on a device by turning on Optimize Storage. See: Set up and use iCloud Photos - Apple Support

Apple does not currently offer cloud-only storage for photos. If that is what you want or need, you may want to explore 3rd party options such as Google Photos or Dropbox.

Another way that photos may be on iCloud (if you don’t have iCloud Photos turned on) is via a backup of an iOS device. The only thing you can do with a backup is use it to do a full restore of a device or set up a new device. The contents of backups are not viewable at iCloud.com and if you delete a photo from a device it will not be included in future backups and will be lost.

The fact that you said your iPhone is backed up daily led me to believe it is backed up to iCloud as that is the only automatic backup option. If you Backup to a Mac (and if you don't have iCloud Photos turned on), the photos are included in the backup. If you delete a photo from your phone and then do backups after that, the photo will eventually be deleted from the Mac. If I remember correctly only 2 backups are maintained and they are then overwritten.

If you import photos to the Mac (not the same as a backup) your photos would be visible in the Photos app on the Mac and are not deleted when you delete the photo from the phone. See: Transfer photos and videos from your iPhone, iPad, or iPod touch to your Mac or PC - Apple Support

If you import photos to the Mac (not the same as a backup) your photos would be visible in the Photos app on the Mac and are not deleted when you delete the photo from the phone. See: Transfer photos and videos from your iPhone, iPad, or iPod touch to your Mac or PC - Apple Support .

Only if they were deleted recently. You can go to Recently Deleted at iCloud.com or on a device. Also see: If you're missing photos or videos in the Photos app - Apple Support