I can only respond for Babylon.js
Actually for question 1, I can respond for both:) they are javascript 3d engines that need WebGL to run hardware accelerated rendering (Three.js can run with pure software rendering as well but do not except to render anything else but a cube). So they can be used for web pages and web apps (ala Cordova or with Cocoon.js)
For question 2, babyon.js uses a left handed coordinates system. You can define transformation on both local or global spaces
More info about transformations in Babylon.js doc: http://doc.babylonjs.com/page.php?p=22041