I am thinking of doing a hard reset my phone. Will the Lumia apps like Glance, Creative studio still be there after the reset without restoring backup?
What are other things that I wouldn't be able to reinstall/do?
If its there then it will remain part of the system. You'll need to reinstall your apps since you're not restoring your backup. After the reset make sure to sign in with your account (Do not skip it). Your tiles will need to be rearranged as you like. Also all data will be deleted with the hard reset. Perform a back up of your important stuff.
Im already in the preview without hard reset since the 10149 build. I find it stable on 10512 however, i cant pin xbox tile on start, cant make live folders, cant uninstall wmpoweruser. I know other 10512 users can do it.