If you are brand new to Construct I would advise starting with Construct 3 as 2 is not supported. Also for your questions I would advise checking out the game Kiwi Story that comes with Construct 3, it will demonstrate the platformer game mechanics in behaviours and events so you can see how one might be made.
1. You can use invisible sprites and their collision or there is a tilemap object which may work as well
2. Not sure what this means, I'm not an artist
3. There is a scroll to behaviour which follows the player. If you mean a camera that snaps to different views then you could attach it to an object that teleports.
4. No idea if you need something special for Switch but maybe a common HD resolution is fine?