#1 no solution
but I had to try two different ways of inserting parentheses before I got your answer. Grrr. The spacing in "t + 2" was especially deceptive.
#4 x = 0 or 2
This time, overkill. Use parens as needed, but only as many as it takes to avoid ambiguity. I'd have said
(x -6)/(x^2-6) = (-4)/(x-4)