You would need a <a href="http://en.wikipedia.org/wiki/Frequency_changer">freqency convertor</a>. This would probably cost you more (if you consider both initall cost of the convertor and in the long run due to inefficency) than a fridge designed to work in the country you're using it in.
nothing
No
As the waffle maker is a totally resistive load there will be no problem using the different supply.
Nothing happens. The stereo has a transformer that converts the power to DC, and 50 or 60 Hz input makes no difference.
It would involve some electronics work but it could be done. Might add that it could be more expensive than just buying the proper power supply. Use Use 220V 60hz motor to run 110V 50hz Generator.
you can't
Yes, no problem.
Yes. the voltages will be compatible. Though in North America it will probably be hard to find 220 volt rated lighting fittings as the common voltage rating for lighting fixtures is 120 volts.
220v 50Hz
Most likely, yes. Most devices has been manufactured with an idea that they will be used in areas where the supply power frequency is 50 or 60Hz.
There should be no problem at all.
220V , 50Hz