Taiwan? Okay then try using smart switch for PC or failing that ODIN. Models not meant for the country they are being used in do not get ROM updates readily. It's up to you to search them out and apply them manually. Try sammobile or xda-developers for the ROM image to use with ODIN if smart switch for PC cannot update it for you.
not really, your phone is a generation behind now. check the current release cadence for it on the samsung website because you may find it now gets quarterly instead of monthly updates going forward (with google play services patches in between)