You only need 1 corrosive. It doesn't stack or depend on the weapons dps. I would make the size 3 incendiary, 1 med corrosive, and the other med emissive. Autoloader for the size 3 would be another good one to counter a little the long spool up times.
It could be that you need to change the corrosive to high cap to counter the ammo loss of the corrosive exp, but test it first with overcharged and go from there. The emissive does help the gimbals to stay more on target, especially a colder running one. Chaff counters any gimbal/turret weapon so in that time either get really close so you hit anyways or get yourself in a good position to unload once the chaff effect is over. I run the incendiary/emissive/corrosive combo on an FdL and it goes through shields and hull super easy.
It could be that you need to change the corrosive to high cap to counter the ammo loss of the corrosive exp, but test it first with overcharged and go from there. The emissive does help the gimbals to stay more on target, especially a colder running one. Chaff counters any gimbal/turret weapon so in that time either get really close so you hit anyways or get yourself in a good position to unload once the chaff effect is over. I run the incendiary/emissive/corrosive combo on an FdL and it goes through shields and hull super easy.