I've owned both the Polarizer and 010M filter for the Canon 24-105 MM and can guarantee you will see vignetting at 24mm with the Polarizer and a slight darkening with the 010M (UV) filters. The slim filters are the way to go if you're going to be shooting anything at below 28mm. The B&W site goes into a bit more detail on what length vignetting becomes an issue but in my experiments with the 24-105 anything below 35mm using the Polarizer will vignette. If you're not planning on stacking filters (which is generally a bad idea with L glass anyway) I'd go with the thin filters and just change them out as needed. I leave the Slim Polarizer on my 17-40 mm about 85% of the time.
I would wager based on my experience with the B&W standard lens filters that you would see some vignetting on both of these filters, even with the 010M I have to be aware of a slight darkening of the edges of my photo if I back off to 17mm ( I currently shoot a 17-40mm lens) The polarizer will definitely vignette. To avoid this issue I'd go with the "Slim" model filters B&W produces for wide angle lenses.
So... these filters serve two different purposes. The UV filter that I purchased is on my lens to protect the first element when I'm in situations that require me to be less than 100% diligent about where my lens is. A hood serves the same purpose so I supposed it is kinda redundant redundant... The Circular Polarizer is designed to reduce glare coming off of non-metallic surfaces. It can add "pop" to landscapes and cloud scapes much in the same way that polarized sunglasses do for your eyes. They do reduce the amount of light that makes it to your sensor and you'll need to take this into consideration. Hope that helps.
The circular polarizer is used to remove glare and darken sky's. You also loose a couple of stops of light, so at night and indoors you will not need it, although it might be effective indoors to reduce glare on non metallic surfaces. If you want to replace it you can use a skylight filter or a UV filter.