RE: bottle conditioning.
In short, my limited kveik experience so far says kveik bottle conditions really well, but requires certain conditions. Here's what I've found out so far:
Cali-common fermented with Skare: my first foray into kveik for a long time. It was drinkable after about a week grain to glass with some bottles being noticably nicer than others. Some were more carbed than others, and the more carbed the better it was. However, the batch was hugely inconsistent with some being difficult to drink and others being the exact beer I wanted to brew. I put some bottles in my fermentation fridge (FF) and after 4 or 5 shoved them in the fridge. First one I had later that day, was ok, still kind of weird. Cracked another a couple days later, was amazing. Had another the next day, was again fantastic. On a side note, I don't think Skare is that clean, had citrus and tangerine coming through.
Sour fermented with Ebbegarden: Really similar story to above. Was ready to drink in a short time, but wasn't too nice and really flat. Where a beer fermented with "normal" yeast is fizzy in a few days, kveik tends to not carbonate. Shoved in the FF for a few days, then left in a normal fridge for a day or two, fantastic! I was so happy with this beer.
Oatmeal Stout: Left half the batch in the FF and kept the other half in the cellar. Tried a bottle after a week from the FF, flat as a pancake. Some bottles have an infection though which seems to be limited to certain bottles. A friend helped me bottle this batch and I left them with bottle sanitisation, they may not have done this properly for half the bottles. It still might be quite young though.
I think kveik needs about a week in the fridge at fermentation temps and a few days in the fridge to fully carbonate and bottle condition. As mentioned, my experience here is a bit limited but I have many more kveik brews which I'm gonna experiment around with to test this theory. It does seem to take longer to actually carbonate though.