Re: Recent Manga Storyline and Tsubasa Chronicles
As for when each occurs timewise, it does move around, and not happen at the exact same time. I was reading the tankoubon (bound volumes) from the library, and what I'd do is: Read the first volume of xxxHolic, then the first volume of Tsubasa. Then two Tsubasa for each xxxHolic since more volumes came out for the former. It wasn't exact, but it kept my memory for events fresh enough to get the references when they happened (and as a plus, the Del-Rey translations have notes in the back often citing the crossovers, it's really a handy tool you don't get in the fan-scans.)
It's less confusing when you have the bound volumes in your hands so you can flip back and forth and compare things when you come upon them. So I actually recommend the physical, translated manga. Use your local library's online catalogue and order the volumes from surrounding libraries if you don't have them right there.
Or even buy them; I sure will when I can afford to. These are the best story/stories ever!
Del-Rey did a very good job, endeavering to be as accurate as possible. A little TOO much; they lost a lot of subtle nuances. But, at least you can be sure they didn't Americanize a thing. They even say in the back once that what LOOKED like an Americanization was, in fact, present in the original Japanese. Or they give American-equivilant examples in the back, but still translate the line itself directly in the book.
The Edited Mangas you can then go to when you run out of bound volumes, but the chapter numbers actually might be different; I ran into that when I was TRYING to compile which xxxHolic chapters connected to which Tsubasa chapters. So it'll take a little trial-and-error to get back on track there, but it's not terribly hard.
Good luck on your upcoming reading adventures! ^_^