Gist
Yes. Bulgarian split squats can provide a strong glute stimulus, especially with useful depth and a controlled forward torso inclination.
Yes, through anti-rotation and balance. The offset stance makes the trunk resist sway, particularly when the load is held asymmetrically.
The front-leg calf works to stabilise the ankle and balance the body, although direct calf training is still needed for the most predictable growth.
They can train the hamstrings as hip extensors and stabilisers, particularly with trunk flexion, but direct hamstring work remains useful.
Yes. The front-leg quadriceps work hard through knee flexion and extension, and the unilateral setup can make moderate loads highly challenging.