Some questions on Unity 5 Asset Bundle usage

According to the example here, and some of my experiments, I got the following questions. (based on Unity 5.0.0f4 personal edition)

• The so called 'internal id' of an asset bundle is not explicitly visible in any manifest file, and it only guarantee that different variant instances of the same asset bundle can be only loaded/downloaded once at the same time using WWW. Is this correct?

• If a prefab X depends on a material Y, and X is in asset bundle A, whereas Y in B where B has variants, the simple manifest file only contains one variant (the one where Y stays). Why? Is this on purpose? And do you have to get dependencies, find the wanted variant and set it back to the prefab in A?

• [Solved] In Unity 5.0.0f4, when the prefab in an A.B. contains some script, errors will be thrown when loaded like 'The referenced script on this Behaviour is missing!' and 'GameObject (named 'LocalizationTry') references runtime script in scene file. Fixing!'. Is this the same as this issue which is said to have been fixed in 5.0.0p2? [I've tested with 5.0.0p3 and this issue hasn't reproduced any more.]

Thanks.