Gaining muscle IS a stress. So at most you've shown exercise pushes the body to adapt to these things.

Insulin resistance is irrelevant with proper diet. If you are eating the right foods you do not need a "strengthened" insulin response.

Nothing you've mentioned improves longevity, they are just isolated indicators. If you have a proper nutrition profile and thus normal weight, along with unstrained exercises like walking and stretching, nothing you've mentioned improves on that. Actualy the opposite is true. Straining your heart and body decrease life expectancy. Blue zones don't have Gyms.