I recommend you focus on using iron sights before jumping on the RDS bandwagon. Daniel Defense and Troy both make great front and rear sights. Since your rifle has a railed gas block... Troy makes a front sight specific for mounting on gas blocks, since a gas block is not in the same plane as the rail on your upper receiver.
https://troyind.com/
https://danieldefense.com/
If you do go the red dot route, I recommend an Aimpoint over an EoTech. I have an Aimpoint Comp M4s and an EoTech 512. In the grand scheme of things, either company's product will serve you well, but the Aimpoint is superior in durability, battery life, and functionality. I do like the reticle better on the EoTech, however.
I don't have any advice to give on magnified optics since I don't run them on my AR-15s.
Your barrel is 1:9 twist, so it should run well with bullet weights up to and including 69gr. Anything above that, and the bullet might keyhole after it's left the barrel. This is due to stabilization. Both of my rifles are 1:7 twist, and I've had great success with 55gr FMJ ammo from Wolf and the ubiquitous XM193. There are some who don't like Wolf, but it's cheap, and it works. Both of those attributes keep me shooting. There are other bullet types to explore from varmint loads to bullet types designed for social encounters (soft point and open tip match). The following links are threads posted by Dr. Gary Roberts, a former Navy ballistician.
https://pistol-forum.com/showthread.php?4344-5-56-mm-Duty-Loads
https://pistol-forum.com/showthread.php?4343-5-56-mm-55-gr-M193-Terminal-Performance-Thoughts
MX on AR-15s is no more difficult than on an AK type rifle. Many regard the AR -15 as unreliable, which is untrue. Keep you bolt and bolt carrier lubricated and you won't have trouble for thousands of rounds, assuming it is an AR-15 built by a quality manufacturer. You can clean the chamber, bore, bolt, bolt carrier, and the insides of the upper and lower every thousand rounds or so if you're anal about keeping the rifle clean. This should take 15 minutes at the most. Don't over clean your bore. I would run a brush once... maybe twice down the bore (chamber to muzzle) followed by a few patches to pick up the extra carbon.
https://www.slip2000.com/blog/s-w-a-t-magazine-filthy-14/
ETA: On closer inspection of the picture of the S&W ORC, it does appear that the gas block is in the same plane as the upper receiver, which would negate the need for the special height front sight. I would confirm this with S&W though.
ETA2: Quoted wrong person.