m.law doubts

hi frnds..!!

 i was going through the consideration chapter of Indian Contract Act, 1872, when these doubts came to my mind. pls help me get it sorted.

1. according to the act, consideration need not be adequate, but it should be real and of some monetary value. but m.law also suggests that services can be conidered as goods. So, if Mr. A agreed to teach accounts to Mr.B and in return Mr. B will teach Economics to Mr.A, so is the consideration valid..??

2. now forgive me for this question of mine, i am not being cheap or i do not want to imply anything else..i just want to discuss this in context of m.law..

     Consideration must not be illegal-one of the rules regarding consideration. according to Indian Penal Code(I.P.C), s*x trafficking(prostitution) is a criminal offence, so if a prostitute has rendered her services then if she asks for consideration is it valid..?? [ actually it is valid, acc. to N.D. Kapoor notes, i want to know how, since this is illegal..??]

help me out guys with these questions..and pardon  me if i offend anyone of u by my second question..