Orthogonal projection onto a plane

Let T:R4R4 be orthogonal projection to the 2-dimensional plane P spanned by the vectors v=(2,0,1,0) and w=(1,0,2,0).

  1. Find (with proof) all eigenvalues and eigenvectors, along with their geometric and algebraic multiplicities.
  2. Find the matrix representing T with respect to the standard basis. Is this matrix diagonalizable? Why or why not?