Well, I suppose I kind of already said my thoughts on Squall in my previous post, but I will say, Kinsao, that it's surprising to me that you feel it is more "cheerful" sounding, just because I feel like it's very sad when I'm listening to it, even if musically it is on the lighter side. ^-^; As for the other two:
Desert: Having Squall and Desert together reminds me of the Kogoeru single in that they kind of busted out a totally different style with Kogoeru, and then when people started spazzing about it, were like "wait wait wait, we still have stuff like this- *cue Maze*" XD Or something like that. Yeah, I think Desert is a nice B-side. Just goes to show you that they may be reaching into new styles with other tracks, but they can still do harder tracks like this quite well. I especially like the part which starts around 2:50. All in all, an interesting contrast to Squall and Screen.
Screen: I also think Screen is wonderful. I was very surprised by it when I first heard it, as it is a very Hizumi-focused song with all the synthed music to go with him. Still though, as it is a song that both Tsukasa and Karyu wrote, I appreciate that they kind of "took the risk" in writing something so different.
Bluuuuh...that's all I can think of off the top of my head, but if more stuff comes to me, as I'm sure it will, I'll just say more about it later. XD
Thanks for sharing your thoughts on it as well, Kinsao!