Methinks many of the things the guys have to collect for their "other jobs" end up in Yuuko's shop. After all, who else would pay to get a man-eating book or invisible fireflies?
Clamp have stated that they are planning to continue it, probably after they finish with xxxholic and tsubasa. And considering they don't start drawing a story until they have the whole plot written down, it's highly likely that's what they will do. It would seem a waste to have ten volumes' worth of plot that is never going to see the light of day. They had to stop serializing it because the magazine where they published it broke, or something, and went off the market. But something similar happened to Clover after they had done two volumes, and they published the remaining ones by themselves. They certainly are rich enough to do that.

Eh, I think Tsubasa was started first, and xxholic not long afterwards. It was almost simultaneous. But xxxholic has had shorter chapters all along, so there are fewer volumes of published material. That's why Tsubasa is a bit longer.

And you won't know him unless you read RG Veda. He was an awesome guy... yet the level of his suffering is not unlike that of Fai... so you can imagine how much Clamp made us Kujaku lovers suffer with his story. ;_;

Actually, Ashura and Yasha are the main characters of RG Veda. And they suffered a heck of a lot more in that manga. Their end in Tsubasa may have been bittersweet, but that doesn't even beign to compare to how much more depressing their ending was in RG Veda... though yes, with a tiny little ray of hope.
But they are still one my favourite couples of all times. >_<

He chases Fai with his swords? seems to me you're too used to talking about Zoro. Kurogane only has one sword... albeit a very long one. XD