iCloud how to?

I want to factory reset my phone. I have a back up That I did 6mths ago, which I want to re-install. Unfortunately since the last back up, I've used my phone...... a lot. Which wasn't supposed to be the case, but is. I don't want to lose some of the content I currently have but the back up version is more important. I'm hoping to add some of the current data [photos, messages, notes etc] back to the phone after I've re-installed the backup.

I'm thinking of saving current data to iCloud before wiping phone.

My understanding is that iCloud syncs with my iPhone. If I delete phone photos, messages, and notes etc etc, then too are they deleted from the iCloud?

Or will those datas still be there ready for me to download later. Mixing the new and old Ito one complete combined data pool

Thanks