During an outage, the inverter will transfer from utility {PHCN} to battery power in about 10 milliseconds for an inverter/home UPS and 0 milliseconds for the online UPS.

Yes. A stabilizer/Automatic Voltage Regulator {AVR} can be used on the output of an Inverter provided the Stabilizer/AVR Capacity is less than the Inverter capacity.

Excessive load may be connected to the inverter.Reduce the load by switching of some of the elctrical loads. Overload protection MCB at the back of the inverter might be tripped. If all above are Ok, call for service assistance

Sine wave power allows your equipment to run cooler, last longer and operate without the malfunctions and reduced performance caused by substandard power. Sine wave power also ensures maximum compatibility with sensitive electronics like computers, network devices and audio/video equipment. Many devices require sine wave power, including variable-speed power tools and computers with active PFC power supplies

The runtime (i.e., amount of time that the inverter will power connected electronics) depends on the amount of battery power available and the load that it is supporting. In general, as you increase the load (e.g., plug in more equipment) your runtime will decrease.