1) yes, just different names for same thing
2) again yes, but unless you have a card reader they won't work on a pc, they are for cameras and the like
3) same as 2, usb memory sticks are for computers, memory cards are for cameras and the like
4) no, a usb memory stick is all you need
5) at six years old you computer is almost certain to have usb ports they look like this
http://tinyurl.com/6j9tt4 may be on the back only or may have couple on front too
6) there is a selection of memory sticks here
http://tinyurl.com/6j9tt4
There is also 2 versions of usb, usb1 and usb2 (they thought hard about the naming!!) they are fully compatible with each other but version 1 is slower, which means if you have USB1 ports on your computer you can plug a USB2 memory stick into it and it will work but will take longer to back your files up.
http://tinyurl.com/5pxrta