Well, aside from red smoke dropping literally 1 second before the air strike and occasional infantry bark, there are no other visual cues about the strike coming in. But we got rather easy to spot buff icon above enemy infantry units, so that your best friend aside from flashing minimap.
Indeed, I know from experience that the red flares are worthless as you're strafed before the flares have died out, much less had time to move. I'm fast but I can't beat physics.
Icon isn't really that helpful, I'm guessing it's a nice crosshair? If so, there's other abilities that do that like Assault and I think the Command Aura? You really don't have time to think about which one of them it is, esp if the UKF player is on a different side of the map and then you get zero indication.
Well, Sector Artillery and Zeroing Artillery are similar in their area denial ability. Of course they also cost more and don't cover as large an area. If anything it can do with a slight cost increase I think. It's not a huge issue most of the time because Advanced Emplacements isn't a good commander overall and Special Weapons has a lot of other munitions sinks.
Ehhhh for Zeroing Artillery you have to practically fall asleep (8-10s ish after the red flares) before the shells start ramping up. Then maybe another 5s before the shells REALLY start landing. At which point, the player has had incredible time for warning and could have been killed up to several times over by other bomb abilities. Imho you really deserve every shell landing on you if you aren't getting out of dodge for such a massive ability and its circles in-game + minimap.