Wow, this will take a moment, but welcome to the forum!
Some of your questions make me think that this is your first time brewing all grain beer, have you brewed beer, or anything, before? This is not the easiest option if your starting out.
1) How did it turn out @Fleecer? @Zephyr259 you mentioned that it is sweet and spicy and hard to drink more than 500ml. Was it initially not great? Did it get better over time?
My brew was a bit weird, as I probably mentioned above (3 years ago) it was my 2nd brew on the grainfather and after getting a stuck mash I chickened out of adding the grape concentrate. So I got a 6% belgian braggot, when it was young, < 6months, it was nice, like a belgian blond but it could have done with more bitterness as it got a bit sickly even though it wasn't actually sweet, hard to describe, just unbalanced. The acid from the grape would have likely balanced it out which is why the recipe states a low bitterness, acid and bitterness together do not taste good. After 6 months mine seems to become very winey and darkened, I think oxidation got to it some how. At this point it really wasn't good to drink, too sweet.
2) How long should I keep it in the carboy before I bottle it? Is 1 month a reasonable amount of time or is 20 days better?
The simple answer is until the gravity is stable over several days. Given this is a 9% brew and is more of a wine than a beer it could take 3 - 4 weeks depending on how it goes.
3) What type of sugar should I add right before bottling?
Normal white cane sugar is fine.
4) The recipe says 4-6 months for maturation. I assume I will taste it at 4 months and see how it tastes but does anyone think this is the optimal time for consuming? @MrRook You said yours took a whole year to get good? Is there a maximum amount of time I should keep it in the fridge before finishing it?
Yeah, as a strong drink it's going to take a while to mellow and the flavours to meld
5) What temperature should I keep the carboy at before bottling?
Dependant on yeast as they all have different temperature tolerance. I'd get this one pretty cool before pitching yeast and making sure it doesn't get too hot while fermenting or you're going to get a mess of fusel alcohols and some very expensive drain cleaner. Likely pitch in the mid teens and keep to 20c at max I think.
6) Should the bottles go in the fridge after bottling?
No, keep them warm until carbonated and conditioned, at least 2 weeks to carbonate, maybe longer due to high abv. Then they'll condition better at cool room temp than in a fridge.
7) Do you think Champange Yeast will produce a satisfactory result? I did some research on this and found: "most wine yeast strains may have a hard time processing maltose, which is likely to land your brew on the sweeter and more full-bodied side of the flavour spectrum" Source:
Making A Braggot - Basic Braggot Recipe
Maybe? There's a lot of simple sugar in this recipe as it's basically 1/3 malt, 1/3 honey and 1/3 grape so a wine yeast should make a good effort as the maltose is gonna be low.
Apparently, Lalvin ICV K1-V1116 doesn't struggle as much as most according to that article. Using a beer yeast is risky as they might not be happy with so much simple sugar. I think I'd mash on the low side and use wine yeast.
8) The Recipe says that the honey and grape concentrate should be added at the end of the boil. Does this mean once the temperature is below 112F?
End of the boil is once your done boiling and about to start chilling. I'd not do that here as it's going to cook off the flavours and aromas from the honey and grape, I'd add them once the wort is cool. There seemed to be contention about honey and if you need to treat it with heat or metabisulfite to kill or wild yeast, I think several of my meads just got mixed and pitched with yeast and they were fine.
9) What temperature did you boil the wort at? The video referenced above uses 160F.
Boiling is boiling, so 100c or 212F, altitude dependent, but that's not much of a concern in the UK.
10) How quickly should I cool the wort? Is faster really better? Is it worthwhile investing in an immersion cooler? I was considering simply using ice and cold water in my sink but my brew kettle has a thermometer near the bottom that I fear will be damaged if submerged.
Faster is better as less risk of contamination, it also affects hops but that's not a concern in this recipe. There is a no-chill method where you transfer to a gerry can after the boil then seal and leave to cool. Small batches are ok in a sink, a full 5 gallons will be tricky.
11) Do I need to mash and then boil the grains or can I simply mash the grains? The video referenced above only mashes, the article referenced above says mashing for 75 min then and boil for 60 min after lautering, the recipe mentions nothing about mashing but just "at the end of the boil"
You need to mash these grains to convert sugar to starch, you then drain the wort (lautering) and boil the wort, do not boil the grains or it will extract all the tannins and you'll end up with something like overbrewed tea.
12) How important is sparging? Can I even do that if all I have is a brew kettle?
13) Is it ok to put the grains in the brew kettle without a brew bag if I have a kettlescreen in my brew kettle?
Sparging helps with efficiency as it rinses more sugar out the grain, you don't have to do it and sound like you're doing brew in a bag which traditionally doesn't sparge and mashes which all the water needed for the brew. I don't know what a kettle screen is, too many results from google. You need a way to remove the grains from the wort after mashing. Simplest option would be a mesh bag designed for brewing, just dont apply heat with it in or you'll probably melt it.
14) Should I be using Five Star and Star San for cleaning before brewing?
Cleaning can be done with most things as long as it's rinsed thoroughly afterwards. You'll need to sanitise anything that comes in contact with the chilled wort after the boil is done, that's were Star San come in, it's your sanitiser and doesn't need rinsed afterwards, also, don't fear the foam. :-)
Think that covers everything. But also what I know now is that fermenting this could be a pain, mead needs nutrients and carefully managed, wine and beer are easier. Hopefully, they will give the yeast what it needs to perform well here.
Good luck. I'm sure others will be along with advice too.