Crawdad Trapping

Hi there,

I am not sure if this message is in the correct place. So if not,
well, sorry.

I want to try my luck with crawdad trapping. I was looking at traps
and well there are quite a few. I see some that are tubular and some
that are rectangular, etc.

What are the pros and cons of using these different geometric shapes?
I will be trying in a fairly slow moving river, it appears to be some
sand with some fairly large rocks. Rocks being couple feet across.
There are places that are swift and othere that are slow movers. But
still some current.

I don't want some cheap traps, but I would like to get the traps
within a week or so. Who's should I look at? I don't want a massive
trap either space is somewhat limited, and I sure as heck don't want
to make one, but I guess I can modify one if necessary.

I see Cabelas and Bass pro have some, but they get mixed reviews.

Any pointers? How about bait consideration? fish heads? cat food
canned? My grandpa used salami, he swore by it, but he's not around
to ask now.

How long to soak these guys? I was planning on throwing a couple out
at mixed places and well, fishing other places with a rod and reel for
fish. so overnite would be nice,