Using STEMS with a Z2 and F1 Setup

These maybe trivial questions but I can't find any information to help me out. I'm using Traktor 2.9 with a hybrid setup using a Z2, an F1 and vinyl turntables. This is my first experience with using STEMS. So I have a couple of questions.

1) I've set my decks C and D as STEMS decks as A and B are for my turntables. Loading a new STEMS into either C or D prompts an error message saying the file needs to be analyzed. Traktor doesn't do this automatically? The workflow seems very cumbersome.

2) Once I've loaded a STEMS track onto say deck C, how do you play it without using the computer keyboard?

Curious

 

2) you don´t need to use C & D as Stem Decks, just use A & B as Traktor automatically changes the deck flavour to Stems when you load a Stem file into a Deck ( loading a normal file afterwards will change it back to a normal track deck)

 

Ah... got it. So though I'm using the turntables to control the track on deck A or B, I'm actually using the F1 to turn on/off stems within the track. Essentially turning decks A and B into a remix deck of sorts. But I can still use the F1 on decks C and D as remix decks. This will take a bit of planning and practice to get use to.