Date of image capture varies with each scene, nominally 2000 plus or minus 3 years. The Landsat program is an ongoing project of the NASA Corporation to obtain satellite imagery of the Earth's surface, with the first Landsat satellite launched in 1972.
The Landsat imagery is not "true colour" imagery, but is instead presented Shortwave Infrared or SWIR, which displays as follows:
Band 7 (mid-infrared light) is displayed as red
Band 4 (near-infrared light) is displayed as green
Band 2 (visible green light) is displayed in blue
A dataset Geocover Landsat 4/5 is also publically available from the same website.