You have asked quite a few questions that could be answered by a little Google work and some reading, but I'll take some of it and leave the rest for someone else.
The CZ-75B comes in a blue plastic case with a manual, a cleaning brush, cable lock, a spare magazine, a snap cap, and an inspectors card that tells you what size group your gun fired at 25 yards. The CZ-75B has a safety, rather than a decocker. The decocker is considered helpful by some (Europeans, mostly, I think) for letting the hammer down safely on a live round, so that the gun may be operated in double-action mode for the first shot, with each successive shot being a single action.
Americans, most of whom are fairly familiar with 1911s, are usually not so hesitant to carry cocked and locked, so the B model is more popular, because it can be carried cocked and locked.
The XD comes with a manual, a cleaning brush, cable lock, spare magazine, and a plastic holster for the gun and one for two magazines, which you probably will replace with something better. The XD45 also comes with a very good magazine loader.
I can't remember if the CZ came with a magazine loader or not.
Both are great guns.