I was going to ask all those questions also but since he wants to do the roof without learning how to do them, without having the right equipment, without reading older posts, without learning from someone, without learning from someone else's mistakes, without putting in some time reading, etc....... Then let them learn the hard way, that is what they are wanting to do since they don't want to learn the easier, right way.
All the info on cleaning roofs is there in the archives, if they don't want to take the time to learn, we can't make them do the job the easy way, let them learn the hard way. It is their time, money and professional image. Let them look like a amateur since they don't want to learn.
O Well, let them learn by pump up sprayer, they will really appreciate reading and doing their learning time like a lot of us have done then they will realize how valuable the older posts really are. hahahahahahaha