Hi Remus, most cameras at the moment seem to have moved away from the base unit at home that you click it onto to charge the battery inside. I assume this is because if you can't physically change the battery when you are out using it you are basically stuffed! :)
The bit above about cards - SD or XD explained....
Some cameras come with built in memory, some don't. Some have a slot in the side for a memory card, either as an extra to the built in memory or as a stand alone memory for the camera.
Lots of computers / laptops / printers ( and the photo machines in Asda for example) have little slots in them which take these cards, so in order to transfer from the camera to you computer or to print in a shop all you need to do is pop the card out of the camera and put it into the machine.
The advantage to doing this instead of connecting the camera to you computer with a wire is that transferring data uses up your batteries v fast ( yes I'm obsessed!
)
Photos, and videos take up quite a lot of memory. I would recommend at least a 2gb This is a good cheap 4gb which is even better! www.ebay.co.uk/itm/4GB-SANDISK-SD-SDHC-MEMORY-CARD-CASIO-NIKON-CANON-/280655056222?pt=UK_AudioTVElectronics_PDAsAccessories_MemoryCards&hash=item4158584d5e#ht_1513wt_1185 It is class 4 which means it has a good fast write speed ( so you can keep taking photos while the camera is sending the last pic you took from the buffer to the memory card) and sandisk are a good make.
XD cards do all of the above, but far fewer things have an XD slot, the world seems to be going for SD and if you buy XD you might make things more difficult for yourself, you can buy adapters, but really, why bother. :)
I will say that if your dd has been using a canon already changing Makes can be confusing for a while, its a bit like mobile phones, I can pick up most Nokias and use them straight away because I'm used to them. Hand me a Samsung and I'm flummoxed!
Hope that made sense. :)