I have a 5600 and I\'m in the UK. The AC adapter comes in two parts, the bit with the switching adapter that plugs into the Zaurus and then a standard lead that plugs into the AC socket with a figure of eight connector that plugs into the adapter box. So all you need to do is get a replacement cable with a standard AC plug on one end and a figure of eight plug at the other end. They\'re only a couple of quid/euros and can be found in most decent electronics stores.
The biggest list of Zaurus apps is at
http://www.killefiz.de/zaurusOpenZaurus isn\'t very stable on the 5600 as yet from reports that I have heard.
Firefox is not available for the Zaurus yet, but the version of Opera that it comes with is very good and has been specifically designed for the small screen.
Cases are hard to come by for the 5600 because of the battery bulge, but it\'s very sturdy anyway and the clear screen cover protects the screen very well.
Don\'t know about the lifespan of the 5600 (Only had mine since November last year), but I also have a 5500 that is 2 years old now and is still going strong (Has been heavily used and only had to replace the battery a few months ago, which is fairly normal for lithium batteries).