Is there a way to create my own type of workout (different from the default main stressor options: Upper Body Endurance, Lower Body Power, Lower Body Hypertrophy, Upper Body Hypertrophy, Upper Body Strength, Mobilty/Recovery, Lower Body Strength, etc.)?

Yes, you can create your own type of workout with any number of tiers and with any exercise that exists in FitForce. In the calendar view, click the + button to add a workout to a date, then select Custom. Click that same date again to access the workout editing section down below. Click Edit and begin adding tiers and exercises. You can re-name the workout as well as the tiers.