1- It depends on the size of your container. Smaller thin containers will make the layers thick, big containers will be very hard to separate small quantities due to thin layers.
2- Dont use coke bottles for extraction, just do a search on 'chemical compatibility' and you'll see PET plastic is no good with lye and organic solvents.
Get a glass or some HDPE container. Any hardware store should have HDPE (look for a triangle with 2 in the middle) containers of a smaller size.
3- Check the
FAQ4- Scale down proportionately. Also check
FAQ for recommended solvent amounts. As for lye, you can just add until the whole thing is black..
5- Having ice cannot have any relation with 'too little base', probably that person did something wrong (like getting water in the container). Too little base can at most result in small yield. If the whole thing is black, though, its enough....
6- You can reuse solvents after freeze precipitation, if thats what youre asking, yes. At most what will happen is that even freezing, it will come out yellow/more impure because with each reuse the solvent will accumulate more plant oils. Thats fine, just recrystallize the dmt afterwards if desired. Also remember not to throw anything away until you are done with the extraction and have your final satisfactory yield.