Well, Opportunist + Suppressive Fire work very well together but you'd need obviously to dump two feats for that. Personally, I'd drop Aimed Shot and Three Pointer. Aimed Shot is useful early game but later on you're mostly spraying; Three Pointer is just really hard to justify.
You're going to be able to get 2 bursts a turn with the Chimaera of either caliber, so really it's up to you. I generally like incendiary bullets more than acid bullets, personally, but acid is a great choice when fighting things that aren't afraid of fire.