Thank you for your suggestions, the first one is already supported in the dev version. We will discuss how to support pre & post build scripts, I also think it's a great idea personally. The last one, you mean unified build directory for web & native ?
Yes, your project will be compatible across the versions, and for major version update, we might introduce some difference, but will also provide a upgrade tool or something.
As for now, we are in public beta, and we haven't reach 1.0 yet, the APIs may still change, it is possible, we will give clear informations about the changes to help you fix issues caused by API change. But in any way, your project will be compatible with 1.0 and future versions.
You can still do the following manually.
cc.view.setDesignResolutionSize(960, 640, cc.ResolutionPolicy.EXACT_FIT)