Same as any hot water heater. Turn the gas valve to off.
If the pilot light is on, the heater should come on by itself. If the pilot light is off then it has to be lit. If it will not stay on, the thermocouple is bad.
Turn knob to PILOT, press button down and light the pilot; hold button down for 60 seconds and release - pilot should remain lit; turn knob to ON. If pilot does not remain lit, turn knob to OFF, wait 5 minutes and try again, If pilot still will not remain lit, replace the thermocoupler.
It is most likely the thermocouple that is bad. That is what keeps the pilot light on. The thermocouple is the small tube that sits in the flame of the pilot and runs to the control valve.
Yes
The detailed directions are printed on front of EVERY gas regulator. - However, in general terms, turn regulator switch to OFF for 2 minutes, then to PILOT and depress for one minute, then light pilot or press clicker till it lights. Keep PILOT pressed for 2 more minutes then slowly release it. If it stays on then turn main switch to RUN or ON. -If you have to light the pilot manually, use a barbecue match (12 inches long)
No because water heaters have a safety valves and when the pilot light goes out the safety valve shuts off the gas
Change the oil.
Yes
The water continues to run into and out of the water heater. There is just no flame to heat it up.
No, it is not dangerous. (Unless you are working with a water heater that is 20+ years old.) In any modern hot water heater, if the pilot light goes out a fail-safe will go off - preventing gas from leaking out. Also, there is a sensor so if there is not enough air-flow or oxygen with the water heater, it will shut off the gas.
When pilot light goes out, gas flows out of the pilot light nozzle. If out has continued for a long time, a gas cloud can develop around the furnace. When you go to light the pilot light, you'll ignite this gas cloud and make a big fire ball. If your basement is drafty, you might never get a huge cloud of gas hovering around your furnace. When you notice that your pilot light is out, you should shut off the gas to the furnace and allow any stray gas to dissipate before you turn the gas back on and light the pilot light. alliedallcityinc.com
Check if your pilot light is on. If it is, then there is a fault in the gas regulator and you will need to call a gas technician.-If the pilot is off, The detailed directions are printed on front of EVERY gas regulator. - However, in general terms, turn regulator switch to OFF for 2 minutes, then to PILOT and depress for one minute, then light pilot or press clicker till it lights. Keep PILOT pressed for 2 more minutes then slowly release it. If it stays on then turn main switch to RUN or ON. Use a barbecue match (12 inch long) to light manual pilots. -If the pilot will NOT stay on, then you have a faulty thermocouple. - Not a complicated job. Call a competent handyman or gas tech.