the trans isomer has forbidden Laporte transitions because it has a centre of symmetry, i? Whereas the cis isomer doesnt have that quality so it will have a higher molar extinction coefficient. Does that sound right?
on the right track, but watch how you word this. I don't like "forbidden Laporte transition", I'd go with "Laporte forbidden transition" meaning a transition that violates the Laporte rule.
I'd say that the d-d transitions in the trans isomer violate the Laporte selection rule (or are Laporte forbidden), which applies because the complex is centrosymmetric.
The corresponding transitions in the cis isomer are not subject to the Laporte rule, due to the lack of an inversion centre in the cis complex.
This stuff should be in any heavy inorganic textbook, or perhaps you can even find a book on inorganic spectroscopy.