The 3 Week Diet
Questions & Answers

I'm guessing you can add tofu. Maybe not legumes, because they're high in carbohydrates. Since there is a portion of the diet that calls for eating extra fat, think mayonnaise, butter, bacon, etc... what I suggest is frying tofu in butter, eating a whole avocado, maybe drinking coconut milk. Be creative, have fun.
Hope I was of some help.

Not sure this diet calls for a lot of fat be added all fats except Trans fats if there are fats in vegan protein then yes most definitely I assume

Yes... just substitute the meats with your protein substitutes...