Is there a way to change the gear layout of your companion ? I noticed they will equip certain items you find and give to them automatically but a way to change exactly what they use would be nice.

You can never take what they have when you get them (Lydia's steel armor, Sven's clothes) but they'll equip anything that's an upgrade. So, if you were to say, give Lydia a Dwarven helmet, she'd put that on. Then decide you didn't like it, you could take that back. So you can choose what they were to an extent.