1. Dunno, I've only ever used powdered cactus.
2. Yea, you can reuse as much as you want. The 'dry mix' will absorb some of the d-limo each pull, so eventually you may have to add in more d-limo for the later pulls.
3. I've never used a tool for this job. I just jar, then shake vigorously in various directions and angles for 1-2 minutes. Then I let it separate out (1-2 minutes). Then repeat, shaking and settling ~5 times. Each shake gets it so thickly mixed, I don't see how a blender could do it better, but using one may be faster.
4.

vinegar is natural and probably the safest acid you could use. I use diluted hcl, though. 8 drops of muriatic acid (31.45% hcl) in 100ml of water creates a diluted hcl solution at the right ph(~4.5)
5. I use acetone to clean mine. I think 99% IPA works the same. I just take the scraped, impure wax and drop it in a shotglass of acetone and crush it up, mix it around. A minute later and the much more clean crystals settle out, and the colored acetone is poured off with majority of impurities. Then let the crystals re-dry before scraping back out. I wash it like this 2-3 times.
6. It's a really easy tek in my opinion. I guess a couple tips are when you mix the d-limo into your cactus, some will get absorbed. It really pays to squeeze back out every drop of the d-limo that you can. Those last drops will have the most alkaloids. The 'dry' cactus mix will be sort of dough-consistency. Can press the d-limo out somehow , I used to use a bucket and a plate. But now I take the dough-ball in an old jersey and wring every drop I can out of it.
Also, when you are mixing the vinegar with the d-limo, the solutions separate like oil and water. But it's very hard to separate every last drop perfectly, even with a dropper. But if you just do your best and collect your 4-5 vinegar pulls in one glass, you can freeze it. The vinegar solution with the alkaloids will be the bottom, frozen layer. And if you have any leftover d-limo, it will be pooled on top, unfrozen. Can just pour it off and wipe off the surface, boom, 99% separated. Make sure the bottom layer is frozen solid though. I poured off the top when the vinegar was still slushy once and half my extraction plopped down the drain.