If you are a professional user, familiar with the precautions to be taken when using creosote, yes you can.
Yes you are, as long as you make sure your client is a professional user and do not sell in packaging of less than 20 litres.
Of course you can. It is just that as a professional user you are still able to use creosote, which has a track record of almost 300 years and offers the best price/quality performance.