[unity 5.5.0p3] Loading indicator for assetbundle scene inside of the game

Hi, i have some questions
a)
i have a progress bar indicator outside of the game and it works fine.
My problem is that i layout the game so my scenes are loaded via assetbundle manager
this one
now when i load an scene using LoadLevelAsync() i show a loading screen/UI with an spinner. It works fine BUT i would like to show to the player how much he has to wait. But i can’t find a way that i can get how much % left has the game when is loading an scene. i tried to get the value read from AssetBundleLoadLevelOperation but i just get 0 or 1.
So, can this be done?

b) How can i pre-load a scene bundled using assetbundle manager, and load it after an specific event ( a trigger or a button pressed)?

thank you

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