1) Play the avatar you want for whatever personal reason you have.

2) The game is not easier or more difficult on console or PC. Additionally, you can use a controller on PC or keyboard and mouse on console if you so choose. I prefer to use both on both.

3) Being a casual player is not beneficial or detrimental in any way. It is a choice, usually but not limited to lifestyle circumstance. What casual and hardcore means differs from person to person and neither are playing the game right or wrong. It's just a preference and you're free to play how you choose, within the restrictions of the ToS.