AC:LR Test Ac 1?

[Black Dragon]

I don't generally use EO much, so can someone enlighten me on how those generally work?

EOs are core types that "launches" floating guns that hover on your back that provide additional firepower.
There are two types of EOs:
One fires energy weapons, these cores' ammo refill when you deactivate them, making them pretty good for protracted battles/missions. The downside is that they waste your own energy when they fire. Another downside is that these cores don't have AMS (anti missile).
The other type are the solid ones. Unlike the one above, they don't use energy and they have AMS. The downside of these cores is that they don't regenerate ammo and like solid munitions, they add additional costs to the ammo costs if they're used. They could also generate heat pretty fast if you don't have enough cooling and they're left activated, the machinegun one especially (E2).

Will it be generally better for me to put RS or a sniping weapon on the right arm? Would it mesh well with the GAEA EOs?

IMO, it would be better to put more bullets in the air with this build. I think the standard rifles is a good choice over SRs