1. Which is the longest video games ever? (longest in terms of hours/days needed from start to finish the main quest)

2. Which game has the most secrets/cheats/easter eggs?

3. Which is the game with lowest review %?

3-Anubis 2 (Wii)

1. According to How Long To Beat, WoW is the longest game but that doesn't really count. Next would be some Monster Hunter games which would makes sense. I know Xenoblade is over 70hrs too
2. no idea :P
3. According to Gamerankings, when looking at games with 5 reviews or more, the lowest is Big rigs: Over the road racing with 3.83% xD

Big Rigs is the worst.

No idea about the other two.

Well the longest videogame is probably some rpg

3. You can check: http://howlongtobeat.com/stats.php

According to that:

World of Warcraft 612h 48m
2. Monster Hunter Freedom Unite 211h 25m
3. Monster Hunter Tri 185h 47m
4. Gran Turismo 4 162h 39m
5. White Knight Chronicles II 148h 31m
6. Gran Turismo 5 130h 49m
7. Dragon Warrior VII 123h
8. The Last Remnant 122h 13m
9. Disgaea: Hour of Darkness 120h 46m
10. Pokémon Diamond and Pearl 119h 46m