1. You answered your own question in #2, they take the Micro Four Thrids family of lenses which will take any lens that is of the Micro Four Thirds mount. However the only lenses dedicated to the Micro Four Thirds Mount are made my Olympus and Panasonic and as you state, they aren't cheap. However.. due to the mirrorless design of the Micro Four Thirds cameras they can easily take nearly any less you can throw at them as long as you have an appropriate adapter.
Like this person who mounted a Canon 70-200 L to a GF1:
2. Not quite sure what you're asking.. but they have all the settings for ISO, f-stop, shutter speed, etc. just like a normal DSLR. The quality of the shots on a.net isn't always based on the camera body, its the lenses that make or break a shot. These cameras may be the size of point and shoots, but they most definitely are not.
3. Panasonic uses standard SD
/SDHC/SDXC memory cards in the 4/3 cameras. A Compact Flash card would be half the size of the body!
Hope this helps!