A double action .357 is a good choice for an all around field carry gun. Over the years I have gravitated to big bore single actions, but that is just a personal choice. I would lean towards a 4 inch barrel length. A 6 inch barrel makes the revolver a little harder to carry if you ride a lot in a truck, or sit in a kayak. Harder to conceal as well. You really give up little by going to 4 inches, especially if it is not your primary hunting weapon. Just make sure you get something with adjustable sights. Blued is nice, stainless is more durable. I don't know if I would buy new. There are a lot of police turn ins that have been carried a lot, but fired little, at real good prices. Any of the big names are good - S&W, Colt, Ruger, Dan Wesson. Stay away from Taurus - from personal experience.
For plinking, or just messing around, you can't beat a .38 spl. wadcutter / semi-wadcutter load. Works well on small game as well. For serious use against lions and bears, I would choose a good full power .357 158 grain controlled expansion soft point, like the XTP. You might get a little better penetration with a hard cast solid, but I think considering the caliber (bullet diameter) a little expansion is good. I once killed a 275 lbs. black bear with one shot, center chest, as he was facing me, with a S&W 586, 4 inch, .357 mag 125 Remington hollowpoint. Not my first choice, but I was deer hunting with a rifle. I had set the rifle down, figuring I would try the revolver. All of a sudden, there he was, 20 yards away. It was my duty revolver at the time, and I was pretty good with it, so I took the shot. 1 shot, he "woofed", spun around, and died. You should have seen the look on his face, I don't know who was more shocked, me or him.
Larry