There are relevant answers to several questions in Astronomy SE:

 - [How bright is the full Earth during the lunar midnight?](https://astronomy.stackexchange.com/q/8133/7982)
 - [How many times brighter would full-earth-shine appear to people standing on the moon, than full-moon-shine does to people on earth?](https://astronomy.stackexchange.com/q/41277/7982)

These are good questions and relevant to the experience of future Moon colonists, where dwellings and vehicles will have "Sun roofs" and "Moon roofs" but they'll be called "Earth roofs".

> - Now large would the Earth be, and how bright, with comparisons, would it be? How brighter or dimmer would it be from the full moon, or a lamp? 
> - Can you read under the light of the Earth? 
> - And I know it would vary, so how bright would be at half full, or quarter full?

Since some folks have "cast shade" on this question of Earthlight, I'll post this answer as partial before a possible closure then continue to work on it.