1. Good luck in your Internet Recipe Hunt. I have not shot any Meister wadcutters and cannot give you one. The Lyman data is a bit heavy for target shooting. You would not go far wrong with 2.7 gr Bullseye or 3.2 gr Win 231 which is what I have used for years, although with other brands of wadcutter.
2. The illustrated bullet has three lube grooves, only one filled for the low velocity typical of wadcutters, and a crimp groove right behind the "button nose." I would seat to and lightly roll crimp into that crimp groove and take the OAL as it came.
3. I do not know what you mean by "mellow .357". How many fps is that?
Would your regular target load, whatever that turns out to be not be suitable for plinking? I doubt you could push this bullet very much faster than .38 Special Midrange levels without leading; it only has one of the three lube grooves filled. Old, old NRA testing showed improved accuracy with enough but no extra bullet lube, right down to one groove lubed in the H&G No 50 bullet, which the Meister closely resembles; which may be where this comes from.
I'd get some semiwadcutters for mellow .357. I would be extremely careful loading them. The only gun ever blown up on our range was a .357 loaded with near maximum charges of Bullseye; almost certainly doubled, 18 grains when 9 was wanted.