It is unnecessary, but very easy to do. The boiling stone can just be a clear marble or piece of broken glass. (Post 214613 (missing)
(Synthia: "Re: GHB purification", General Discourse) found by searching for "boiling stone ghb").
It can be done safely in a home kitchen, with the standard disclaimers. Make sure no passerby can see in the window. Wear goggles and gloves. Use the right glassware, and don't put a hot piece of glassware in cold water.
It does not matter whether the water you add in step 12a is already boiling or not. I'm guessing this is just so you don't use cold water and crack your beaker. Try to make it at least room temperature though.
Or you can just add water after the GHB has cooled and solidified. That will also give you the chance to weigh it first. If you don't want to do that, just weigh the beaker beforehand and then weigh the water that you will be adding in step 12a. Then weigh the beaker again with after step 12a, subtract the weights of the water and the beaker, and you wil get the weight of the final product.
I think using NaOH is a little easier, but baking soda is much safer. (Post 283264 (https://www.thevespiary.org/talk/index.php?topic=9661.msg28326400#msg28326400)
(Chromic: "Re: GHB synthesis - a must read", Methods Discourse) and Post 283023 (https://www.thevespiary.org/talk/index.php?topic=9661.msg28302300#msg28302300)
(Chromic: "GHB synthesis - a must read", Methods Discourse) found by searching for "baking soda ghb"). If you insist on using NaOH, the form is not important, only the purity. Use food grade, not lye.
I don't know what material a crock pot is typically made out of, but if it is glass, you should be fine. Otherwise you would be better off buying a corningware (or other glass) saucepan.
As for the amount of water, go by Chromic's write-up: Post 283023 (https://www.thevespiary.org/talk/index.php?topic=9661.msg28302300#msg28302300)
(Chromic: "GHB synthesis - a must read", Methods Discourse)
That seems like a good procedure, if you choose go the NaOH route. Nowhere in the post does it say to microwave anything or remelt the cooled NaGHB immediately before pouring it into the gatorade bottle.
Besides, unless you are making massive amounts, it only takes a couple minutes to dissolve.
edit: according to http://www.matweb.com/reference/deflection-temperature.asp (http://www.matweb.com/reference/deflection-temperature.asp)
, the melting point of Polyethylene Terephthalate(PETE), the platic commonly used in Gatorade bottles, is 250C. So it should be able to handle melted NaGHB.
The melting point of HDPE, on the other hand, is only 130C, so if it comes into contact with hot NaGHB it will probably melt.