I think you should go to a TKD school to have some classes. (prefer ITF if you can). You can learn stances and drills from youtube, but i think the best way to understand the logic behind it, is to have some sparring...
For them, it all comes down to speed and reflexes... You must either be faster than your opponent, or choose the best counter to his strike.
You step/jump in and out a lot... You must be able to change directions quickly, stop on your tracks moving backward or forward, jump at any moment... That means also a lot of work on balance.
Since they don't have to worry about low kicks, or strikes to the back. And since fast movement in and out is more important, that explain the blade footed stance. It also makes a smaller target, and allows to use your rear leg for spinning shits faster.
Downside is that your rear roundhouse, side kick, or teep/front kick, will travel a bigger distance. Same for the rear hand punch. Will be slow and from an awkward position.
They are light on their feet, since they don't try to block heavily like MT. They prefer to counter or evade the strike.
Lots of them prefer to have their good leg in front, for faster reaction, but every experienced one will be able to fight in both stances.
They use a lot of body feints, that why they constantly move/bounce...
They are very good at measuring distance, without the use of a strike. (jab/teep/low kick). They don't spend a round trying to figure the opponent, distances etc. As soon as the match starts, they go at it. But if they have to, the front leg side kick is the best tool for that.
They don't really switch, they just change stances. And it's a huge deal, since depending on what stance you have, what stance your opponent has and what strikes he throws, your counter will be different.