I can't see why you'd need to- PROVIDED you have already listed him as someone who lives there and included his income in any household income figures.
1. No, you don't need to report it. It is not income - it is simply to cover part of the costs you incur (council tax, fuel, water etc.) in prooviding him with accommodation.
2. He is not included in your tax credit claim - he is regarded as a separate household (which is not the same as the house he lives at) - so you would not put his income on your claim form.