But I know of no software that allows this. R makes it extremely difficult to understand codings. They are very obscure and easily lead to errors of interpretation. That is my whole point. As in I stated above, in a part that you cut, to pay attention to the contrasts options that I set.
Single levels are at least as relevant here as for any other contrast set.
The coefficient for WM is minus the sum of the other three. Some statistical software packages very nicely print out the coefficients for all levels instead of arbitrarily dropping the last one. They could get very cumbersome. You have lost me here. The answer is, of course, No.