Yes, when people get splatted they create an AoE explosion that will take down anyone directly next to them and harm ones further away. As for beakons, i'm not sure but does it obscure the entire hitbox of the Inkling or can you still shoot over the beakon and hit the target behind it?
As for Zones, do you use vanilla Luna or Neo? I'm not a blaster main but Neo sounds better for zones, Splat Rush can very quickly take an enemy zone while deterring enemies from getting close to you. The kit saved me a few SZ matches w/ the Splatterscope.