1) wavelength = speed of light( 3x10^8)/frequency which comes out to be 767 nm.
as 1nm =10^-9m
2) The frequency and wavelength have inverse relation. so, if frequency is doubled, the wavelength becomes half. Red light wavelength is around 700 nm, so doubling its frequency means half wavelength i.e. 350 nm, which comes in the ultraviolet region( specifically near-ultraviolet region 300nm-400nm)