If you search the Workout Library for “fitness test” these entries will list.
As @wescaine mentions you want to ride the workout to failure during any intervals designed for that purpose. To ensure that outcome, ride the workout in Slope mode, not ERG Control (called AUTO in Xert).
As to question #2, workout selections will depend on calculated form and which program type you select. For example, if a TED (target event date) is set far enough in the future, you’ll be in Base phase of a timed progression where only endurance level workouts will be recommended. In Xert that includes both easy endurance (LTP and below) and hard endurance (LTP to TP). As you zero in on your target event date and move from Build to Peak phases, focus duration will begin to narrow to your target duration (Puncheur).
If you select Continuous as the program type, workouts will reflect selected Athlete Type when calculated form is Fresh (blue/green). If form is Tired (yellow) only endurance level entries will be recommended.
Regardless of current Athlete Type selection you can always change suggestions on-the-fly by using Filter. For example, you could set Focus to Road Sprinter if you wanted to insert a sprint workout into your training.
Lots of newbie tips posted here – Beginner questions
Academy series videos are the quickest way to get up to speed – Discover + Improve + Perform
FAQs here – Support Home – Xert