I'm going to check out the ceramic. I'm fiddling with 2 DID clones at the moment as I've got a Provari on order (I say that so proudly). I've altered the DID clone with a second wick hole to make the horseshoe from the wick. I can get a much longer set of coils now in a half moon around the center post. At McMaster they have the ceramic sleeve rated at 1100 degrees, I'd like to use that over the center post to protect the coil. I also need a 1/32 drill bit so I don't destroy another DID top, not that it can't be repaired, a drop of silver and re drill smaller.
As for cotton, I use square braid cotton candle wick. I got 40 yards for about $10 or $12. In the Vivi mini, it works great, lasts several days. I fray the ends outside of the coil for even better wicking.