Cross Platform Migration using different modules.

1. A qualified yes. But you may need to manually remove the ASM config entries.
2. Yes, you can add a 3rd member at a DR site. But you can't vary between sync-failover and sync-only in the same traffic group... What I've done is add the DR site member(s) and then use HAGroups with gateway monitoring to ensure that the DR unit ONLY goes active when the DR is enabled...

I'm not aware of any soln articles that explicitly talk about this. And yes, you probably could go the SCF route. However I like to use times like these as an excellent way to cleanup the configs, so listing the config and then building it from scratch again (Using a script obviously) is usually my favourite method.