There are rare times on rare old cars this is required.
All current North American sold and virtually all European sold cars this is not needed.
No
It does no harm to disconnect the battery when working on a vehicle but in general no, you do not need to disconnect them to change a filter.
Changing fuses is not a hard task. Make sure the car is off, disconnect the battery if need be, remove the correct fuse, and push a new fuse in its place.
u need wrencg to disconnect battery then u need socket wreches to remove starter motor bolts
Chang inf a battery on a Nissan Altima is very easy. You will need to remove the bar that is across the battery and then disconnect the battery cables. After the cables are removed, you will take the old battery out and put the new battery in place.
easiest way to disconnect is to remove airbag fuse from vehicle. why you need to disconnect to remove a radiator is beyond me, the radiator has nothing to do with the airbags
you probably need to change your fuses you probably need to change your fuses
no
Generally the solution to these problems is don't disconnect the battery from the car. In order to change you battery you need to connect a small 12 volt battery to the terminals before you disconnect the car battery. It need not be a large battery since the drain will be minimal and the time short. A set of flashlight batteries works fine. Mercedes are particularily difficult because you loose the radio among other things if you disconnect the battery. You must get a dealer to reset it. This negates anything you save by installing your own battery. Note a battery charger also works.
You more than likely need to replace the headlight switch. Lights not going out when turned off is a symptom of a bad headlight switch.
to change o2 sensor ,you need to buy a o2 sensor socket from a parts store then disconnect neg terminal on battery ,after that disconnect wire connecter on o2 sensor and remome o2 sensor
all you need are wrenches to disconnect battery cables, and sockets and extensions to remove starter blots from starter