Amber versions are tough because you have to balance the sweetness from whatever cara malts you are using to give you color with the English yeast that already leaves the beer a tad sweeter. The one amber 1318 NEIPA I made was good but a little cloying. You have to go higher on the first...
Juice is totally not 1318. I think it's closer to 002. Only 1318 is 1318 (so far that I've tried). s04 is more like 002 imo.
I'm from the Tired Hands school of NEIPAs and 1318 is a must.
For primary in a keg, you can depressurize the keg, pop the lid, let 1-2psi CO2 run into the open keg while you add the dry hops and if you really want you can purge your hops with CO2 before you add them. I'd use a keg float and semi crash the keg for a day before transferring over to a serving...