Ebay is always a good place to buy, House of Hybrids, Stormy's actually looks pretty good.
I believe 325 is going to wick thicker juices better than 400, I personally prefer the 400 for anything ranging from 60/40 on up for the PG side.
Kanthal is going to have a slight break in period, some say a tank or so, I say about a half hour lol. Nichrome has no break in, but will warp slightly after so much use, and may need to be adjusted if your using a stainless steel wick.
32 gauge is going to be lower resistance and thicker, 36 will be thinner and higher resistance. When building a genesis out of the Vivi you'll find the wick leaves a small amount of space to work with for coils, I'm able to get a wrap showing 3 on one side and 4 on the other. I mainly use 32 guage Kanthal a1, and with a wrap like that I'm floating between 1.2 and 1.5 ohms meaning the VV devices hang lower than I thought I'd be using them at when I bought them lol...my Provari hasn't gone over 3.4 in a few weeks now.
Hope that helps a little.
How is the DID treating you?
I'm still anxiously awaiting mine.
Quite well, I had to rewrap the coils angling the wick away from the brass nuts, but I keep my DIY Jr Mints in it at all times. I will say that I'm enjoying it more now that I've drilled the air hole some and got my SS Ming in the mail, best drip tip ever.
I'm interested in TommyG's just out of box impression of ViVi tanks
I was really hopeful for at least one of the two I received today, thank you Hoosierecig lol, I filled both up with the juice I wanted to use in them and soaked the coils pretty good. I took them out to the garage while I got some things ready to mod the dud, and wound up modding them both...they were great until I vaped what I had personally put on the coils, then it ran dry. Now I'm up to 3 Vivi genesis', and a lone DID. The Vivi is still a fantastic platform for modding into a few different tank styles, Genesis (personal favorite), scuba U shaped wick, a proper CE style with a little wick hole drilling I've heard, or done up with cotton wicks. For 15 dollars I don't think it can be beat.