Ropes you need to bring: 60m-65m. Those ropes cover 99% percent of rappels in Crete canyons.
For canyons like Arvi (Rmax 82m), Lapathos (Rmax 80m) or similar. there are middle points that you need to reach and change ropes. if you can not do than bring a 90m rope. One in a team (group) is fine.
The neoprene suite you need to bring with you is 5mm or 5.5mm. water in Crete in April is 10-14 celsius degrees