If I reset my phone, but my photos are on iCloud will I still have my photos when it resets an I log into my iCloud ?
Yes. If you have iCloud photo library enabled, and all your photos have been uploaded, your photos will still be on iCloud. Just enable it again. Tested from 8.4 to 8.4.
Yes. As long as you have your photos being backed up using the Photos Library, your photos will be saved. To be sure, you can always go to iCloud.com and log in. There, you can use the Photos web app and see your photos. As long as they are there, you are safe.