The opera house traps open back up the same way they fold up (I'm assuming that the ones you bought were flat when you got them so you know how they open up).
As for a line setup, most just use rope and tie it to a stick stuck in the mud on the shore. (I am not sure if dpi rules mean that u technically need a float on the rope somewhere or not).
As for bait, most fruits are good, rockmellon is my choice. The general theory of redclaw for most people is that since they can get out of the pots, you use something like cat food to get them there, than something that takes a long time to eat (like fruit) to keep them there.
Hope this helps