I've split this into a new thread as it didn't really have anything to do with the thread you added it to.
1) It depends on how you are planning to configure RAC and what type of storage you are using. If you are using NFS, or some cluster file system, then the voting disk is just a file on the shared disk. If you are using ASM, then the voting disk can sit in the disk group, or be placed in a separate disk group.
2) Once again, it depends. They have to be on shared storage, but that can be a cluster file system or on the block devices via ASM. It depends what you choose to do.
3) A LUN is a Logical Unit Number. It is presented to the server and seen and used like a single disk. The LUN can actually be a combination of many disks, with or without mirroring/RAID.
4) The voting disk is tiny (about 256M) so give it about 300M to be on the safe side.
5) Depends. Using vmdk suggests you are using virtual disks. I certainly wouldn't consider that for something real. If I were doing a production RAC installation on VMware, I would use NFS for the storage. It's easy and works well.
6) There is no concept of local disk in RAC. They all have to be shared.
7) If possible, always get the mirroring done by the hardware, not ASM. It performs better and is the recommended option from Oracle's perspective.
Note. I can't give specific answers as there are too many variables to consider. It would be wrong of me to make out I can give you a simple answer as it depends on your infrastructure. I constantly have to compromise what I consider "the right thing to do" because of constraints in the company I work in.