Are there more powerful fairies like Aos Si or (Un)Seelie?
Did the fairies go by names before they came to the school?
The ones that go to the school didn't, no. 
Now that they have arrived at the court, do the the fairies have names? Or are their names just Red, Blue, etc.?
It is unknown at this point. 
Is Gunnerkrigg court and the forest both in phayrighie region 4?
A part of the forest is. 
How do phayrighies and their clothing differ from region to region as your region 6 phayrighies have vastly differing clothing to the suicide phayrighies?
Their clothing changes depending on what they find laying around to make their clothes. The region 6 fairies have all the trash of a city available to make clothes. 
Are phayrighies born with the dots on their arms or are they tattooed (or something similar) on at an early age?
They are born with their dots. 
Do faerie regions differ vastly in size, and is there a normalish size for them?
They differ in size but are usually very small at any given time. 
Was the turquoise haired suicide faerie born with the head dots or are they cosmetic additions?
A lot of the fairies are born with different markings and hair ornaments. 
Is it required that the faeries' region be identifiable by looking at them, as the only faerie I can remember having covered shoulders had dots on the clothing there?
One's region markings must be visible at all times. It is usually highly unfashionable to cover one's shoulders but even a fairy with bad taste must show what region they are from. 
I saw one particularly beautiful drawing of a faerie... I believe it said something like 'Region 6 faerie'. Have you worked out a fully detailed concept of faerie communities, and are you thinking of a 'standalone' faerie comic?
Yeah, I have several characters that make up Region 6. You can see two of them on . Ogee is the one with blonde hair, and Polo is the one with pink hair. There are a few others that make up Region 6 and I had a few stories for them in mind. Another thing I might come back to in the future. They won't in gunnerkrigg Court though, since Region 6 is in a city (the same city Zimmy came from).
In the City Face story, one of the fairies asks "where" the other will be back rather than "when" (as one might expect). Does that mean anything for the way fairies think in general?
The fairies don't follow a linear timeline. They tend to use location as a constant. 
Are ordinary people aware of the existence of city fairies?
Not really. 
All of the Regional Fairies we've seen thus far are female. Are there any male Regional Fairies? Or, do all Regional Fairies just look like human females?
There are no male Regional Fairies 
How do Regional Fairies reproduce without males?
Not sexually 
What are the names of the two phayrighies we met in chapter 8?
They did not say. 
How old are the suicide fairies?
If you mean Red and Blue and them other ones, they are the same age as Annie and Kat. They are in the same year. 
Is Red's accent based on some real-life accent, or is it something you made up?
I just made it up, bearing in mind the type of education the fairies have. 
Is the Red Fairy unique in the way she acts? Most faeries from the forest are more even-tempered, right? She might just happen to be more...um, boisterous than the others?
Each of them are pretty strange, but Red is quite unique. 
It was mentioned regional fairies "come of age" when they are able to make their own clothes. Had Red & Blue reached that point, or were they still considered children according to regional-fairies custom?
They reached that age, but they didn't go through the proper ritual. That's why their clothes are so boring.