There's no reason to think the K3 won't work with Calibre, but it can't be added to the software until the devices are actually out.
Speaking from a K2 perspective, since the K3 isn't out yet.
Yes the meta info and covers come across just fine.
The series/tag info will help you stay organized in Calibre, but collections for the Kindle are created on device.
Be careful adding to many books at once, I'd add them in chunks. When I first got my K2 I added 300-400 books all at once. It's the only time I had problems with the K2. It would lock up and the battery life sucked. Turns out that when you add books the Kindle "indexes" them for faster searching and my problems were caused by it getting overloaded indexing all those books at once. Since then I add books in smaller chunks and have never had another single issue with it.