C++
People? Varies. I'd guess ~100 is about normal. Pretty dynamic though & tends to start slowly...doesn't make sense to have all 100 there from the start & do nothing.
Time? Varies. For big games 1-3 years, but often much more.
Programming language varies, some are coded in Python...
However, C++ and C are the best because you have total control over all the parameters, meaning streamlined gaming! Especially graphics, that can be a monster in resources, so you need something that can control those resources...
Also, depends on the game how many people are working in it, but ~100 sounds fair... also, remember, it's not just coding... It needs animation guys, graphics guys, marketing, AI, game play, testers, and also games these days actually have story lines developed for them, just like the movies, so you need voice actors, script writers, scene play guys... All in all, it's a flipping involved process.
Time, well, seems like 12 years for Duke Nukem

.
As SaladCharger said... Almost all main game production houses develop their game engines over time. Battlefield 3 will use a lot of API's from Battlefield 2, 1942, Vietnam, etc... All because it's cheaper to reuse, than it is to make new stuff... So say the body movements might have been done well in Battlefield 2, they will reuse that particular code, and just modify it a little to add new features on top ( like take a pee movement...)