[@Masterkeun] I think you're definitely on the right track, but there's still a bit to go until your sheet is completely ready. I like the additional details, but I'm not sure why members of other families are in the family sheet. That should only really happen if someone is an in-law. For example Jon is not named Targaryen, but he is the family patriarch and is a vital part of the family, just as how Catelyn Tully is a vital part of House Stark as the matriarch. But you wouldn't consider the Stark kids to be Tullys even though they have a Tully mother. So these more collateral relatives can be part of the story but it should be more closely involved Freys who are focused on in the House Sheets, especially if they have the family name. You can also leave it more open-ended so that there aren't quite so few Freys left, in case anyone wants to jump in and possibly play a Frey. And you can use the lesser Freys as NPCs for the important ones, Walder basically sired an army of people and that army grew exponentially (and was probably cut down a lot too) so no reason you can't have the House Leader's squire be a Frey for example. You also need more details for the Frey PCs you include in the House Sheet. Malkor and Jem Rivers seem important, but lack a lot of detail for example.

But all in all, you're definitely on the right track and it's good to see your sheet shaping up so well.
[@Dredigan] Do you have any additional comments or input? 

[@EnterTheHero] So the Alchemist Pyromancers wouldn't be able to shoot flames out of their hands, but with the resurgence of magic, wildfire is easier to make and even more powerful and dangerous than it was before. The Pyromancer's probably won't make as much since Dragons are back, but the Alchemist's Guild could still do all kinds of semi-mystical chemistry awesomeness. Basically like Alchemy in any fantasy story, except probably without the turning iron into gold stuff. A Pyromancer could come up with all kind of flame-based chemical weapons, like possibly an oil they can slide on a sword to make it burst into flames or maybe some kind of reduced-potency wildfire grenade. You can get very creative with this. 

Red Priests, they will have all the same abilities they have in the books, which are a lot but also seem to depend on the specific Priest's talents. Shoot fire balls, heal, see visions of the future, increased life-span, illusion, communicate through fire, there's a lot of stuff a Red Priest can potentially do. I don't think the return of magic would change much except perhaps make their abilities easier to do and maybe rev up the potency a bit. 

Common Sorcerers who are Pyromancers, I kind of imagine them being like Firebenders crossed with Green Lanterns since they seem to be able to make fire "constructs" and can probably manipulate fire like any fantasy pyromancer can to burn and scorch. They seem to be mostly limited to the East however. 

Again though magic-using characters will be scrutinized so that there won't be too many of them, and they are at least a little bit balanced. Additionally, IIRC using spells in the story took a lot of energy to do, and that would still be the case. I think for the RP right now, either Alchemists or Red Priests would make the most sense in terms of story and plot relevance and Alchemists would be more common than Red Priests. 

[@Enzayne] Thanks, for your interest. There are a lot of less prominent Houses, so it might be easier to use canon than come up with something out of scratch but it's totally up to you. Me and Dredigan are at your disposal if you have any questions or want any input from us. 

Did you have a particular region in mind for your low-profile House?