I'll refer you to my original post. You may want to go ahead and invest in the Wilson case trimmer. If you get it from Sinclair, it's available in three configurations. The one with the micrometer, besides being very expensive, is really not necessary. Case length can be achieved without that much attention to detail. Sinclair's base is very popular, but the basic tool can also be bolted to a block of wood and mounted in a vise, should that not be inconvenient. You'll need the case holder for your cartridge. A note: some cartridges, not 300 WM, have a holder listed for unfired cases. Should you ever adopt one of those cartridges, you probably won't be trimming your cases until they are fired. As long as the resulting case length is even, any tool will work. However, being able to maximize the length protects custom barrels from erosion. For the relative cost of a Lee setup to the Wilson, you may want to make the investment early.Could you give me a list of the case prep items you would recommend?
If you wish to uniform your primer pockets, get a tool that has a fixed cutting depth. Some, like the RCBS, have adjustments that can move, and some others are totally indiscriminate. Redding and Sinclair are both good tools. Uniformed primer pockets give the ultimate in reliability, but I doubt that you'll see any benefit to accuracy.
Many do claim an improvement in accuracy from de-burring the flash hole, but it may be undetectable with a factory chamber/barrel. Sinclair's Gen II tool is very popular as it doesn't index on the case neck.
An inexpensive ball micrometer allows you to determine the variation in neck thickness of your cases. You can sort out the worst cases and use them for plinking/etc. rounds.
Sinclair makes an excellent run-out gauge that will let you assess the straightness of your prepped cases and loaded rounds.
I'll go ahead and answer your question regarding neck turning. It is for fitting the case to the dimension of the rifle's chamber, which requires a custom barrel. It won't salvage bad brass.
The only immediate decision you will need to make is the choice between case trimmers. The Wilson is more precise, and a smoother tool, than any of the other options. None of the other tools discussed represents a replacement decision and can be acquired at any time in the future. The ball mic is something that you can acquire early on and see benefit.
I'll suggest one more thing, and it may draw criticism. Get a copy of Glen Zediker's Handloading for Competition, available from Sinclair. It contains very advanced material, but is a complete education in loading. The author's writing style is unfortunate, making comprehension more difficult. However, there's no better source for the material, and nothing nearly as complete. Don't believe everything he has to say about Harrell's equipment. You will have what you need unless you decide to load at the range.
I'll again suggest that you're in a planning stage rather than acquisition. Don't be in a hurry to buy any more than the basics except where future replacement is a contingency. Decisions are no better than the information on which they are based, and the longer you wait to make a decision, the more information you will have acquired.