There are some threads covering these questions and a search will pull them up I'm sure.
Tanning men does not need to be any different to tanning women. The force of the air coming out of the machine will seperate the hairs and make sure that the solution gets to the skin.
IF the man is really really hairy then you can spray upwards instead of downwards as this helps to blow the hairs out of your way and makes sure the solution gets to the skin.
I have never needed to spray upwards but it is a tip that is there should you find someone really hairy.
As for tanning men while mobile I don't really know what to say to you, it is the same as tanning a woman and your safety is important so make sure that any booking you take is one that you feel safe going to.
I always make sure my boyfriend knows where I will be and aprox how long I should be there and he knows to ring my work phone if I am any longer than he expects to check if all is ok. We have a word that I am to say if something is not right or if I want him to come to the address where I am, it is a word I wouldn't say at any other time to him.