I feel like with oil, the more water you can put in the better. Less air displacement and less diffusion = better flavor. Personal preference though. I know people who don't use water all, and their argument is what are we filtering out at that point? We're dabbing pretty much straight cannabinoids/terps at this point with how good extraction techniques have gotten in the past few years.
Any 14mm female nail will work on your rig, and I'd also look for a carb cap. As others have said, becareful with chi TI. Highly Educated is your best bet as far as quality goes as Felonious Monk said. Task from HE also just dropped hybridized quartz dishes that screw onto the dualiti / infinity nails which are pretty baller too. Cool thing about these nails too is they makes sizes that fit both 18/14 and 14/10 joints so you don't need multiple nails / dropdowns for different rigs.
If you have no price limit I'd look at a quave / DC banger and a QFZ/ capstars cap. They're pretty pricey and you'll end up spending a couple hundred, but completely worth it IMO. You can also q-tip your banger after every dab and keep the quartz looking brand new so it looks super clean. Quartz is my favorite surface for sure and bangers have been all the hype for the past year or so, but with good reason. If you're playing no games and that's not good enough look into the sapphire nails from d-nail as well as their silicone carbide. D-nail is an incredible company, and I'd check them out ASAP if you got dollars to spend. They do a ton of R&D and it's all backed up on their website.
Glad your homies got you a dedicated concentrate rig. Smoking flowers/hash or tobbacco/hash out of the same rig is no bueno.