why arent motors mounted at a slight downward attitude in profiles as they are in r/c planes? and also wings mounted in a slight doward position on c/l planes?

   Some people use downthrust (in tiny amounts) on stunt planes. It's an entirely different reason from R/C, but it sometimes is beneficial.

     I am not sure about the second question - I think you mean negative incidence in the wing. We sometimes do use the equivalent (positive in the stabilizer), once again, in tiny amounts and for a slightly different reason.

    Brett