I just started reloading, and bought the Lee 50th Anniversary Challenger breech lock kit, based on feedback here and from a few experienced buddies. I'm very happy with the quality and it's cheaper than the starter kits from RCBS, Lyman, etc.
My kit came with the Auto-Prime (hand priming tool) and it works great. The kit also comes with a prime on the press doo-dad but I'm using the hand primer. I did discover that during decapping if the prime on the press doo-dad is not installed on the press ram the punched out primers fly all over the place. Simply put the prime on the press doo-dad onto the ram and every punched out primer spits right into the disposal tube. Thanks to Higginson for sorting me out on that one.
I'm using Lee perfect powder measure and Lee Safety scale that comes in the kit, and until I get more confident I weigh every charge. I have no experience with other measures/scales but the Lee stuff seems to work well. Like SuperCub mentioned, I set the measure to throw a charge close to (and lower) then what I want, set the scale precisely where I want it, and balance it manually. Instead of a trickler I'm using one of the Lee powder dippers (a dipper and shellholder comes with the die set) and shaking a flake or two into the pan until the scale balances. I'm loading .223 (light charges 22 - 26 grains) and trying to get get exactly to 0.1 of a grain charge weight, so it's literally a flake or two to balance the scale.
The metering screw on the powder measure is calibrated in cubic centimetres, and comes with a reference table that will allow you to set the meter to the correct volume for most powders known to mankind. This will at least get you into the ballpark and you can then either tweak the metering screw until you get what you want or "throw low and trickle up" as I do. As others have pointed out, the Lee measure may not have enough capacity to throw the charges for your 300WM.
I guess the benefit of a turret press vs a single-stage would be the time savings as you perform all operations to produce a loaded round sequentially and don't have to change out your dies. Changing out the dies on the breech lock press is only a 5 second task anyways as the breech plug snaps in/out of the press frame and the die stays adjusted.
In my case, the objective is accuracy/consistency (not volume) and I enjoy the extra time the single stage system forces me to spend on each round.
Hopefully this does not escalate into a flame war about single stage vs. turret ;-)
I'd also suggest that whatever you buy you also get at least two loading manuals from bullet manufacturers. In addition to the load data they are great references to help you understand the process of reloading and how to stay safe. I found the Hornady and Nosler manuals very good.
Hope this helps, not confuses....