For dilution you need water that doesn't have
any chlorine or chloramine in it. As long as your well system isn't adding any chlorine you will be fine. Test the well water with the OTO test and if it is zero then you can use it.
Dave is usually really good about answering e-mails. I'm not sure what is up, perhaps he is on vacation. He has sounded quite serious about the $15 minimum in the past.
You can order directly from Taylor and they are said to ship very quickly. Try
this link for the various sizes they offer. You probably want R-0871-C, which is a 2 oz container.
You are very very close. There is still some baquacil somewhere, probably in the pipes or filter, that is consumming chlorine. It is best to burn the last of it out before lowering your chlorine level or you will have trouble holding an appropriate FC level.
The fact that the OTO test only shows TC is problematic, but given how close to the end you are you could probably get away with it for a day or two. You can get a vague sense of the CC level by watching the OTO test for several seconds right after you mix the drops in. With CC there will be a color shift over the first 30 seconds and without CC it will go to the final color directly after mixing.