Be warned ahead of time. 6" .357s are harder to find. 4" .357s were the standard for duty use, and still the most common length. They're easier to handle and don't lose any appreciable accuracy.
For S&Ws:
The K-frame .357s. Built on the original .38 Special frame, it's a "Carry a lot shoot a little" guns... inspired by Bill Jordan and others as the "ultimate cop revolver" in .357. Fits the hand well, easy to shoot and light. The S&W 19, 13, 65 and 66 are K frames, generally found in 2.5", 4" and sometimes 6", along with the rarer 3".
The N-frame .357s. These are the Model 27/28, built on the .44 frame, and were the "First" from 1935 on till the mid 50s. Bigger, heavier gun, little recoil though. A bit heavy to carry.
The L-Frame .357s. These have the K size grip frame, but when practice all the time with full-power .357s became the norm, to stand up to the additional pounding the K's weren't designed for. This is the current generation S&W 581/681 and 586/686 wheelguns. They're slightly beefier than the K frames, but otherwise, very similar in size and weight.
The K frames are being phased out, but are the perennial favorite for carry guns in .357. The L frames are just as popular, but some people are picky.
As to what to know, anything written by Bill Jordan (who was a primary shaker/mover behind getting the Model 19/66 released as the Combat Magnum) on revolver shooting is good. Ed McGivern, and Elmer Keith as well.