I can't see numbers here, so here are all the answers:
1) the frequency is c/λ = 3e8/556e-9 = 5.39e14Hz
2) light travels at 299,792,458 m/s. So in nanoseconds it's 0.299792458m. This is about 1/3 of a meter which is about one foot.
3) length is L = ct = (299,792,458 m/s)(6e-15) = 1.799e-6m or 1.799μm