System Selection - Electric Furnaces

I currently have gas heat but because of the recent increases in gas rates would it be advisable to switch to electricity?
If you are in a colder climate it is not normally beneficial to change to electric from gas. In milder climates a heat pump can be installed but electric heat is the least efficient way to heat your home.
I see the terms "upflow", downflow", and "horizontal" used when describing furnaces and air handlers. What does this mean?
Is it important that my ductwork match up exactly to my new furnace
I am considering replacing my existing furnace. Any ideas?
Where can I get more detail and specs for the equipment I am interested in?