Q: iPhone iCloud

Hi. In fact you can't delete photos from iPhone and leave them on iCloud. But you can sync your iPhone with a computer and upload photos to your computer saving them there. After this you can delete photos from iPhone.

You can use iCloud Photo Library (especially since you have the 200GB iCloud storage option):

iCloud: Use iCloud Photo Library on your iOS device

As the above article explains, you can't delete the photos on your device without also deleting them in iCloud, BUT:

Optimize storage on your device

When iCloud Photo Library is turned on, your device can optimize its storage by keeping smaller versions of your photos on the device. All your full-resolution originals are stored in iCloud Photo Library and can be downloaded at any time.

• Go to Settings > iCloud > Photos (or Settings > Photos & Camera), then tap Optimize [device] Storage to turn it on.

When your device needs more storage, it automatically replaces some full-resolution originals with optimized versions. If you want to replace optimized versions with full-size originals, tap Download and Keep Originals to turn it on.

Other useful links:

iPhoto: Access your photos and videos everywhere with iCloud Photo Library

Get help with your iCloud Photo Library - Apple Support

iCloud Photo Library FAQ - Apple Support

Hi

yes, you can. Turn on iCloud Photo sharing . Settings > Photos > iCloud Photo Sharing. It'll do the needful.

If you're using multiple  devices, you can turn on iCloud photo stream Too.

one problem here, you can save upto 5000 photos/videos only. That will be on the iCloud. You can delete it from your iPhone.