No, this is an EF-S lens designed specifically for APS-C sensor cameras. It will not mount on full-frame DSLRs like the 5D or 6D series without vignetting or potential mirror damage.
Yes, the STM (Stepping Motor) technology provides near-silent autofocus, which prevents motor noise from being picked up by the camera's internal microphone.
No, this lens does not feature weather-sealing. It should be protected from rain, heavy moisture, and dusty environments.