I aslo recall being told that gas was cheaper and I suspect that stems from the introduction of North Sea gas.
It is difficult to give a simple answer to your first question becasue it depends on what you are using the gas or electric for and how efficient the appliance is. For example gas cookers were historically much cheaper to run than electric ones and whilst that is still probably the case electric cookers are now far more efficient and the difference in running costs much less.
Bear in mind that gas prices are likely to fall next year.
It is cheaper to use a kettle for your pint of water and you will save by using a smaller wattage kettle but not much. When using a kettle firstly make sure that you cover the element but only use the amount of water that you actually need.
To boil water for one cup of coffee tales about a minute but to boil a full kettle can take about 5 times as long. The energy wasted boiling the unwanted water is enough to run an energy saving light bulb for 9 hours.