Not sure why so many suggest a free floated hand guard, the only advantage it gives is the ability to mount more useless crap on your rifle that does nothing to improve shooting. People will say it's for the improvement in accuracy, I've owned AR's with non free floated that would shoot 1 moa and I've owned AR's with free floated that would not. The quality of your barrel is where accuracy comes from so unless you are willing to also change your barrel I would leave the handguard stock unless you feel that you must mount some more stuff on it. The improvement in accuracy with the factory 16 inch barrel will barely be measurable but the weight increase definitely will be.
You can buy rail sections with an angled base that mount to the stock forend which would allow a forward grip or a light and they cost a fraction of a nice floated handguard which would leave a lot of money for ammo.
If you want "upgrades" the only thing I would buy to start out with would be a nice comfy pistol grip. After that shoot it and see what works for you and what feels off to you, then start changing the stuff that feels off.
The factory trigger will smooth out after a few hundred rounds and after 1000 you'll know if it needs to be replaced with something better. Better is also related to what type of shooting you mostly do, if you like standing and ringing gongs or doing 3-gun you'll want a different trigger than if you like sitting at a bench shooting paper at 300 yards so you need to do some research when the time comes. One of my favorites is the ALG enhanced nickel boron coated single stage, it costs about $100 and is an excellent trigger for the money.
Personally I like my AR's light weight and accurate, I build my own now so I pick and choose everything but even after owning so many AR's over the last few years that I can't remember how many there were I would just leave your rifle alone for now and maybe change things later. If you want to change everything you may as well just sell it and buy a higher end AR since it would probably be cheaper.
I know a lot of the fun is tinkering and personalizing it but nothing will make it perform better than you learning to operate it more efficiently through professional training and also simply from putting a lot of lead downrange.