1)only the 60d is sealed, but not well enough for a downpour. Either camera could be used in a light drizzle.
2)only the t4i has video autofocus, put for photos both will work pretty much the same.
3)sadly both cameras will be discontinued in January, so there will be a new substitute for either. If you can't wait, get the t4i, it has a new processor, so it performs better, and the processor has been tested. The only issue, is that the video af is slow, and there were specific models on which the grip changed color but those were recalled and they have fixed the issue since.
4) the weight off the 60d is a bit hefty, and will weigh on you at the end of the day. The t4i will perform the same, it's just in a smaller body, it will fit in your purse without making your shoulder hurt.
5) battery life, I don't know, but will be enough either way, on a vacation, just charge it up at night and your set. The touch screen is ok, just remember it isn't a smart phone, so give the camera a second before you start clicking it rapidly over and over, it has to shift the glass for live view (LCD view) shooting.
So in conclusion, the cameras are very much the same, and you won't notice a difference in image quality. You pay for what you get, the bit of extra $$$ is just for a more solid body, if you think you're going to drop the camera accession ally, the 60d would be a worthy investment.
Lens wise, a canon 75-300 F4-5.6 or a canon 70-300 f4-5.6 is usm if you have the money, would make a great telephoto.
Standard zoom would come in a kit
60d:18-135 3.5-5.6 is
T4i: 18-135 3.5-5.6 is STM II
So again, the t4i really does everything better, it is just smaller.
But if I could choose, I'd go for the t4i with the kit lens! And with the saved money, get the 70-300. You get a smaller, lighter camera, and then you have better lenses.
Have fun shooting