In the US, both 120v and 240v will be needed for your home, as different appliances need different voltages. Your TV needs 120V, while your electric dryer and stove will need a 120V/240V supply. If you have an electric water heater, or central AC unit, they will need a 240V supply.
it won't work properly
As long as the power supply allows you to toggle between 240v and 120v input, Yes.
You cannot use 2-120v outlets to power a 240v dryer. You can convert a 240v dryer outlet to power 2-120v outlets if they are supplied with a neutral. This requires a competent electrician. Do not do this yourself.
No, you must break it down to a 120 volt supply.
You can use 120v 10a 125w cable projectors 110-240v power in India.
Power adaptors are readily available that plug into Australia's 240v outlets, converting to 120v. Find them in travel, luggage and electronics stores.
the simplest solution is by connecting two 120v 3amps heater in series , the same can be used directly on 240v. However the current drawn will still be 3 amps & Not 1.5 amps. The heater output power will be double that of a single heater running on 120v. ( or equvalent to two heaters operating on 120v. supply ) A more expensive method is to use a stepdown transformer which can be powered on 240v & connect the heater on the transformer 120v side. this method will consume approx. 1.5 amps from the 240v supply.
No. The neon sign is fed by a step-up transformer. Primary side 120V, secondary side 7500V. If you applied 240 to the primary side you would get 15000 volts on the neon tube. A flash over and then nothing. If you can find a transformer from 120V to 240V or 240V to 120V then you are good to go. Connect 240V to 240V side and you will get 120V out the other, connect the 120V side to the neon sign and you should have light. Transformer should be at least 100va. This will give you an output of .83 amps at 120V
yes
120V takes less energy
You can using a transformer, but you won't have as many amps available. 5000 watt generator @ 120v = 41.66 amps 5000 watts / 240v = 20.83 amps