It would be nice to know the year of your Nissan Altima. For Nissan 2000 Altima GXE the air filter is located right next to the battery. Just push off the 4 clips that hold the top of the filter housing and pull the top off just enough to remove/replace the air filter. Close it and and pull the clips back on.
alternator or bad wires
around $20
My edcated Guess would be to open the hood, unscrew them and replace them.
no if your battery light is on and the brake light on then your alternator need to be change
Because there is a hole in the hose! Replace the hose
If just the knock sensor need to be replaced. I would say no more than $150.00
It cost me less than $3 if you talking about the bulb...not sure about the cover too
The mirror is held on by bolts on the inside of the door.
It is common to have a knocking or clunking noise of a 99 Nissan Altima, even after the struts have been replaced. This may be due to worn ball joints. It is best to replace the ball joints, too.
It's probably your Alternator that is going bad. That is if the battery and brake lights came on at the same time.
Depending on where you go you would usually be charged between $50 and $150.