My Canon Powershot G10 does not show up in 10.7.4

Just because it supports the RAW formats, does not mean the USB connection will work. Most digital cameras data transfer work better if you just connect the media card to the Mac via a media card reader, and then you don't waste the camera's battery reading the photos. Current MacBook Pros have SD card readers. I don't have time right now to lookup your camera, to find out if yours supports SD. If it doesn't, there are plenty of card readers by Sans Disk and/or multifunction printers with card readers that support other formats.

Canon camera's dont' mount in the Finder. All the other ones do. Why? You'll need to ask Canon about that...

You don't have to install any software. Image Capture can access the camera. (So can iPhoto and Aperture.) The camera is not a disk, and it will not act like one in the Finder. Image Capture gives access to many more features than a mass storage device in the Finder would -- for example tethered shooting and synchronizing the camera's clock (assuming Canon supports those features).

That's not normal. It should show up in iPhoto and Image Capture. If not, something is wrong, probably with the camera or the connection. Check the cable? You are turning the camera on, aren't you? (some people forget...)

It is a big problem that has existed with digital cameras since the beginning. For whatever reason, they fail to use the HID standard properly, or test for its compliance. Apple uses this standard with all its devices. Image Capture may be a little more forgiving than iPhoto in terms of seeing the camera, so you might want to try that, with its variosu preferences.