what will i need to do before restarting my ipad mini and will it even help

my ipad mini has been fragging *** lately, freezing up, not charging right, takes forever then goes right through it in about as much time, Ive had this a little over a year and i read an article about resetting to factory to help the freezing, drag ***, force closing. if I did this what would i need to do prior ? back up photos of course, will the app store remember my purchases, what if an app i have was obtained because the dev gave me a code to purchase, will i be able to reload that, is their a diagnosis app or something i can use to see if i even neeed to reset, like if i have a virus, slow glitchy app, too much data cached? im newer to yhe ios so im not clear on all this, any help or pointers would be aporiciated , i know my info isnt as thorough but i dont know what settings i would need to screen shot or link to give that info, if you need anything to help me out just let me know thanks