All of the above sounds good to me. Just to encourage you, don't make this stuff harder than it has to be. Black powder is probably easier and safer to load for than smokeless - at least for the ranges shot in CAS. You already have the advice you need, stop listening and just load the things.
To summarize:
.357, 38 sp, .38 long colt case doesn't matter, select what ever functions in your rifle well.
Pour in enough BP to hit the bottom of your bullet when it is seated, and then just a tad more so that you can feel it crush a bit when you seat the bullet. Cut or file down a case that will scoop up that amount of powder, epoxy a nail onto it and you have a cheap powder scoop that works. Unlike smokeless you don't need to even measure it to some exact grain amount if you follow that recipe.
Select a bullet that has a couple or so grooves for lube and is soft, SOFT. no harder than 20-1.
Lube: if purchasing pre-lubed bullets make sure that a BP lube is used. If casting your own there are many fine recipes or you can buy something like SPG. But actually a simple tallow / Bees wax mixed 2 to 1 works. Melt it in a pan, set your bullets in it and when it hardens pull them out.
Powder: buy any BP either 2f or 3f.
I have never seen primer type make a difference at the distance shot in CAS.
Have a great, great time. This stuff is easy. Baring smoking over your reloading bench you can't screw this stuff up.