Galaxy S5 acting up

Hello, I'am new to this forum so i hope i have posted in the correct area. I have a Galaxy S5 that periodically gets hot during charging and general use with slow charging and very fast battery drain.I regularly close all my apps but my data is being chewed up at a very rapid rate also.There is no problem with my home modem but my wifi keeps on dropping out and trying to reconnect.I even get message while away from home to say that I'am connected to my home wifi even though that's impossible.I don't hammer my phone excessively with games, Facebook, Youtube & the like either.I have Norton paid version installed and also the free version of lookout which finds no issues. Any help much appreciated.