I haven't used the 24-70 to do IR work, but from what I have read, it should be capable of it. Some lenses have a coating on the glass which blocks that spectrum of light, but I saw the 24-70 on a list that says it will work.
As for exposures, in good daylight I typically shoot at about 3-5 seconds, f5.6, iso 100 with my 50mm lens and an R72 or iso 200, f5.6, 1-2 seconds if it is breezy. Depending on your subject matter or the amount of shadows / shade, you will need to expose for longer. This usually gives me a decent looking exposure / histogram on the LCD, somewhere in the middle. You probably won't see highlight or shadow data on the historgram because of the monotonality of the image caused by the filter, so don't expect a nice looking highlight to shadow histogram. And once the file is open in PS and you remove the red cast caused by the filter, the image tends to be a tad underexposed. But it is a good starting point. Here is one I just did last week, iso 200, f5.6, 2 seconds.
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