Leather Dye is a permanent dye that cannot be removed afterwards.

Shoe Colour can be removed afterwards (and shoes can then be dyed a different shade after cleaning).

Shoes can be cleaned with methylated spirits (using a dampened piece of cloth).

To prevent the polish from cracking afterwards. Stuffing shoes exposes areas where cracks could occur after applying the product in the event that they were not stuffed.

No, suede shoes cannot be dyed as this causes the shoes to harden. Instead, use Suede and Nubuck Renovator

Yes, shoe colour can be used on both synthetic and fabric shoes

Yes, it is necessary.

Shoes often have a waxy layer on them. If you don't clean and prepare the shoes properly this waxy layer can result in an uneven dye effect.