1 filter is disposable, toss it and get a new one unless you have personally verified its re usable
2 is pcv valve, take it out, shake it, if it shakes it suppose to be good. It's easy to replace. My understanding is the small arrow on the valve points to the hose for best results.
3 plug in front is probably hood open detector, for remote start. It's probably not for the grill shutters as if they are unplugged it will set a code