NEIPA...hazy..from lots of flaked adjuncts,oats mainly it seems,but what else? Also hazy from the large amounts of hops..
Pretty much. 10-20% oats or oat malt is fairly typical. Some people swear that adding a dry hop at 'high krausen' or at the peak of active fermenting aids flavour development and improves haze.
Water adjusted for hops and mouth feel?
Yes and no, not essential but again some people swear by their specific chloride to approve ratio, it can get very technical but you can also make a good NEIPA without focusing on water treatment (your water depending!)
But the enemy is oxygenation?
What causes/ enables oxygenation?
Can this style be successful without closed transfer?
Yup, oxidation of hop material can ruin both the bright orange appearance typical of the style, and people often describe the oxidised flavour as 'cardboard'.
I've had good success by bottling (flip tops) straight from primary, with a wand, and being careful to avoid unnecessary splashing/mixing etc.
Given the style I typically drink those bottles between 7 and 28 days from bottling, and I currently brew on a 2 gallon scale. Any bottles older than that tend to lose aroma and haze, and drink more like an IPA (note, these beers are not oxidised, just they lose the pop of a freshly brewed NEIPA).
As for a grain bill, from memory my knock off Hazy Jane (originally from Brewdogs DIY-dog PDF) is 2.5kgs Maris Otter, 300g porridge oats, mash and boil to 9L final volume, 30 IBUs from whirlpool, dry hop with 40g of Citra and 40g Mosaic 3 days before bottling.
My water is hard and this doesn't seem to ruin the beer.