That depends on the Amp-hour capacity of the battery and the power requirement
of the TV when it's on.
If the TV isn't designed to operate on 12 volts, then it won't run at all, no matter
what the capacity of the battery is.
Unless it is a 12 volt DC box fan you cannot run it at all. If it is a 12 volt fan the time it will run depends on it's size and at what speed you run it and the condition of the battery. All you can do is try it.
Yes but you will deplete the battery quickly.
This will depend on the size of the 12 v battery.
No, you will need two 12 volt batteries connected in series to give the 24 volts necessary to run the pump. It will not run on 12 volts.
Charge it with a 12 volt battery charger.
Yes, as long as it will fit in the space provided.
Possibly but but not for long. The 12v motor will draw more current than the 9v battery can supply and the undervoltage will cause the motor to run hotter than normal thus shorting its usefull life.
No
12 volt
As long as the ATV is wired 12 volt, not 6.
No, if they are wired in series you have 36 volts assuming each battery is a 12 volt battery. They will have to be wired in parallel to output 12 volts. In that case you can charge them with a 12 volt charger but it will take 3 times as long as charging just one 12 volt battery.
It takes between 8 and 12 hours to charge a 12 volt battery at 2 amps. The actual time will depending on how much charge is in the battery initially.