@#4 See this discussion:
https://jimlaurwilliams.org/projects/seychellePaper/ Also check out the pdf attached. Cupric chloride is very good and completely reusable. Ferric chloride is also reusable, as the iron is not consumed, but in time and after a LOT of etching, the ferric chloride bath becomes a cupric chloride bath. You need to reoxidize the iron or copper, and there are various ways to do that. Bubbling air is the easiest. Ozone or chlorine are faster, and chlorine bleach ends up adding additional alkali and sodium. Chlorine is not really practical for home use. I thought of using an ozone generator, then decided I didn't etch enough plates for that to be necessary. The cupric chloride batch can do plenty of plates between rejuvenation.
@#5 I believe chemelec has a post somewhere describing his pre-etching electrolysis method. The answer is that so long as the tracts are connected together or in some other way other to the electrode, you can plate away the copper and end up having only a very small amount to remove by etching.
John