Any shampoo containing harsh ingredients such as parabens, sulphates and silicone are bad for hair. You should check for the ingredients before selecting a shampoo. Pantene also has sulphate free varieties.
Vitamins such as Vitamin A, E, D, B12, Roboflavin, biotin and folate are important for hair growth. Micronutrients such as zinc, selenium and iron, if deficient can cause hair loss and /or greying
There are no quick fixes. Have a balanced diet with greens and proteins.
There are no quick fixes. But good nutrition, clean scalp and less tools improves the hair quality and thicknes.
It entirely depends on level the burn took place. For mild burns hair regrowth usually takes places once the scalp gets healed.