No problem.
You have the right CP/M Plus version, good.
Documentation is fun if you are into what you're doing. Problem is that not everyone will read it!
To your specific questions (which, I hate to say, are covered by the document

):
1. The short answer is "use uIDE-16 with CPC6128/464 computers, uIDE-8 for the rest".
uIDE-8 supports 8 bit port addressing. Most Z80 computers use this, apart from the Amstrad 6128 (and 464 I reckon). So uIDE-8 decodes the lower half of the address bus. For the 6128 I had to extend it to decode the whole 16 bits of the address bus, because that machine uses the OUT(C), A instruction, which (not well documented) puts all of BC on the address bus, and the 6128 takes advantage of this to extend its I/O port range. So, in order to support it, I needed to decode 16 bits instead of 8, hence "uIDE-16". This board can be run in 8 bit addressing mode, though. There is a jumper to select.
2. Shim vs. adapter. If you use the adapter you lose access to the expansion port, because the adapter has no through connector. But you do get a composite video out, plus access to all the special signals on the expansion port. Left/Right shims exist so you can choose the orientation that fits best in your machine. Remember, it is "universal" in that it can be connected to any Z80 computer - not just the PCW - and so there is this option. The Schneider port type is not supported, unless it has the same footprint as a 50 way IDC header (in which case you could solder it to the board and plug it into the machine). You are probably best off with a shim / internal solution.
3. Z80 bus cable is just a standard PC IDE ribbon connector, as the page explains. They are cheap and easy to acquire so I do not offer them.
4. Regarding cpmtools. The download link includes disk definitions for the uIDE CP/M format, so it's covered. If you go with a shim you have the option of running the cable out of the bottom right hand corner of the machine and having the PCB external; that gives easy access to the DOM / CF card (plus, you get to see the drive activity light, BONUS!). Alternatively, cut a slot in the machine (they are not exactly collector's items!) and mount the uIDE behind it. Then you can access the DOM/CF card any time.
Re: newbie: Never apologise for asking questions, I welcome them. How else can anyone learn? Just try to not ask the same question repeatedly... and read the documentation provided. Here endeth the lesson...!
One more point - be aware of the limitations. For example, it does not support cold booting the PCW.
Now to supply. I do not have all the parts required to start making them again, so there will be a lead time. However, I do not expect payment until all items ordered are ready to ship.