No problem, glad to help.
1. I bought it right off their website, right from that link, basically. I remember it said something like that when I added it to my cart, but it seemed to go through with no issue. Maybe try it again and see what shows up in the cart. Worst case, you could probably call them and place an order.
2. I remember studying the following links, if you haven't seen them before:
This guys also has a nice write-up/analysis of the work he did:
Here's the way I've been doing it... you remove the motor assembly (keep in mind there are two sets screws on each shaft in the stock ES coupler), so that you can turn the worm by hand. I used a 5mm drill bit inserted into the coupler, so I could really get a good feel for the adjustment and rotate it fairly quickly.
Then you loosen both bearing blocks, and then squeeze them together while pushing the worm into the follower (or wheel). (You're basically trying to prevent any lateral slack in the worm between the bearing blocks, while getting a rough mesh adjustment.) Once the worm's making full contact with the follower gear, while still squeezing, you should tighten the bolts for both bearing blocks - but not all the way, just enough to hold their position.
Then tighten the inner bearing block (closest to the coupler) a bit more. With a straight-edge up against both bearing blocks, I used an adjustable wrench to fine-tune the angle of the inner bearing block to sit flat against the straight-edge. Then I would slightly loosen the outer bearing block to make it sit flat against the straight-edge, while still keeping axial compression on the worm.
The next step would be to turn the worm to move the follower all the way around, to find where you feel any binding. Whenever it binds, I would slightly nudge the outer bearing block away, while keeping the squeezing/compression that was established from the first couple steps. Once there is no binding, and it feels smooth with a full rotation of the axis, I would then do a final tightening of both bearing block bolts, while holding them with the adjustable wrench to keep them from rotating, checking their alignment with the straight-edge as needed. A little extra backlash in RA is no problem, but in DEC you want to minimize it. Sorry for the lengthy explanation, but hope this helps! It gets easier with practice!