On the electromagnetic scale, what as the longest wavelength? the shortest?

Answer 1

That is correct.
The Radio waves being very very big, physically as large as a house.
But the gamma rays being as small as a quark (which makes up the particles in the nucleus of an atom)
So quite large differences in scale here

Answer 2

No reason to stop at either end. Radio waves are usually called the longest, but the waves from a/c current are longer still. At the sharp end, you have the highest energy gamma rays, from cosmic events.