Have you changed anything else? This happened to me once when I bottled on top of a new table that was a few inches higher than I was used to. It took a lot more force to cap and I broke a few before I figured out the issue.
High alcohol beers can take a while to carb. I made one at 10% that was mostly there at 4 months, but I don't think it converted all the priming sugar until about 8 months.
Since your beer is flat it should be easy to take a hydrometer reading. Your 0.8oz/gal of priming sugar should have...
If you're making white wines I'd say the kits are definitely worth it. Reds are a maybe. I personally enjoy them but I don't think they taste quite the same as commercial. Either way just stick to high end kits. Among the bigger brands that's Cellar Craft Showcase, Winexpert...
It sounds like you've mixed enough. Maybe try a pair of bottles once a week and see if there's a difference. Ideally you'd take one that you bottled first and one you bottled last.
You could also try an experiment. Make a similarly thick syrup with some food coloring. Pour it into a large...
Since you're in Oslo you're probably using a kit that most of us are not familiar with. It seems to be a "no boil" kit, maybe similar to Mr Beer.
It should not be an issue that you started your beer at fermentation temps (7 to 13C). It may take a bit longer than the 14 days the kit is...
My stab at these:
A) Oak powder is still oak - it's basically leftovers from making the "fancy" types of oak. People don't like it because it doesn't look neat like those perfect little cubes, so they assume it's crummy. Only issue is there's no way to remove the powder once you have enough...
I did this the other week. My 5 gallon saison finished higher than I wanted at 1.013. I added 12oz dissolved corn sugar and gave a gentle stir. This raised it to 1.020. A week later it was down to 1.011, maybe 1.010.
So it can work, but be careful you haven't hit your yeast's alcohol tolerance.
Here's a clone
https://www.homebrewtalk.com/f39/fans-rolling-rock-i-saw-clone-beer-magazine-recipe-inside-269953/
You can also buy one from Austin Homebrew
http://www.austinhomebrew.com/product_info.php?products_id=1121
They don't share recipes online, but it'll come with the full...
Get to know your equipment ahead of time. The demo will probably use something that you don't own. Then you can ask if there's a substitute piece of equipment or a different method to work around it.
That's an sg of 1.020 after 4 days? Sounds like you're on the right track. I'd leave it alone and check again in a few days. If you have a sealed lid you might need to release the pressure periodically.
Are you putting the o-ring on the inside of the bucket?
I used to do that and it always leaked. I haven't lost a drop since I switched to the outside. This seems to be what Northern Brewer is recommending here:
http://www.northernbrewer.com/documentation/BeerBasic.pdf