I have no clue where to start to replace headlamps on 2005 Cobalt

Its hard to fit your hand in the small space so best to remove the 2 bolts on top 10mm that are holding the headlight in place. The from the side, pull/pop the headlight assembly forward and out from behind the front grill area. Once its out, you can easily turn the retaining collar and remove the bulb. Be sure not to touch the glass of the new bulb or the oils from your fingers will create a hotspot and shorten the bulb life. Replace in reverse order.

You can reset it with the battery for 30s just remove the negative plug

Have you tried to do a hard reset? Disconnect your battery for 24 hours. And try it again. This will usually fix a lot of computer malfunctions. Good luck.

replace the temputer sensor

if you are used to hearing the fuel pump but cannpt hear it anymore, it's probably a fuse or the pump. Pump replacement is expensive, so always make sure the pump is getting voltage before replacing.

disconecting the battery should reset the pcm. but you will need to find out what caused the problems.

i dont think you can just get the chip,its the complete power steering control module (
computer) typical problem withall ions and cobalts

oil change

There will be adjustment screws located on at least two different spots surrounding each headlamp. By turning these screws you move the angle of the headlamp. Most shops will do this at a very resonable rate, I say this because improper headlamp angle may lead to a ticket, or at least a warning. To say the least, they have to be at specific angles and heights. Good luck.

try to locate the fuel pressure regulator, and unplug the vacium hose going to it, if you smell or se fuel at all, that means the fuel pressure regulator is bad and need to be replaced