How are regular medals tracked in Battlefield 1

You have to select the medal that you want to "track" before you start a round. Only then will your actions reflect in the medal.

For example, you have to select the medal and THEN get 20 kills as the assault class.

From this article.

In Battlefield 1 you can earn and equip different weapon skins through Battlepacks. For whatever reason, you can’t just equip these skins at the Soldier Menu on the Main Menu.
You will actually need to be in-game to switch your skin. Before you start a match you will have to pick a class. Remember that certain weapons are only open to certain classes so make sure the skin you want is actually on the class you are playing. Let’s say for instance you have a M 18 skin. Select the Assault Class and customize it with that weapon. When you have the weapon equipped click Triangle, or Y on the Xbox(click on "modify" for PC), and you will get some more options. Here you can switch a few things but at the bottom you can change the Visuals. This is where you can equip a new weapon skin.

You can also change skins on planes and tanks.
If this wasnt what you asked for then I'll try to find more info.