There are a whole lot of different species of crayfish, which to the untrained eye look all together too similar, with incredibly different behaviours, preferences, and suitability for pond stocking.

The primo crawdad for pond use is probably the Papershell Crayfish.

The worst is probably the Rusty Crayfish - they destroy other crawdads, will eat all the plants out of a pond (thereby depriving small fish of habitat), and actually can get you fined in some places for introducing an invasive species (6 figure fine for introducing Rusty Crayfish in Colorado last year!).

Here are some threads with crawdad info that you can peruse for much more detail:

crawfish

Brettski's Papershells

Crawfish? - taste and survivability

GW's Crawdad thread

Additional craw info

AQUANIC on craws - all the info you want plus some.

http://aquanic.org/beginer/crawfish/crawfish.htm

Male above - Female below - pic

http://aquanic.org/images/photos/la/d0564/img0044.jpg

Male right - Female left - pic

http://aquanic.org/images/photos/la/d0564/img0027.jpg

From Bill Cody.

Here are a couple of good threads on crawfish.

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=25641&fpart=1

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=110189&fpart=1

And from Theo :

Major PB Crawdad thread: http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=25597&page=1

There is an entire section in this link on transporting live crawfish pg. 5-6 .

http://srac.tamu.edu/tmppdfs/8989590-SRAC2402.pdf

Add this to your considerations.

Abstract.—We attempted to control a population of papershell crayfish (Orconectes immunis) in an 11-hectare fish-rearing impoundment in Jackson County, Wisconsin, by using traps and by stocking largemouth bass (Micropterus salmoides). Crayfish were harvested with traps during the summer of 1985, and the pond was stocked with 386 largemouth bass (mean weight, 1.1 kg) in spring 1986. The pond was drained in the fall of 1985 and 1986, and crayfish burrow counts were made to estimate the population. In 1985, we trapped more than 18,000 crayfish, of which 72% were adult males. Trapping had minor effect on the young-of-the-year crayfish. In 1986, the crayfish population was reduced by 98%, predation by largemouth bass being the probable major cause of the reduction.


Northern Crawfish info: Seagrant link

Rusty Crayfish info and identification: rusty crayfish invader