This images are ment to be used in Oracle VM, not in vmware as they are "Oracle VM Templates for Database...". You could try to convert those ovm images to vmware image, there are different ways to do it, vmware has got a tool called "VMware vCenter Converter Standalone"( I've never used it ), qemu-img can be used as well.
Another option is to use Oracle VM, which is free to download and use, and then you could use this images following the product's documentation in the link you have provided "http://www.oracle.com/technetwork/server-storage/vm/documentation/dbrac112040-ovm-tmplt-test-config-1979323.pdf" for test and "http://www.oracle.com/technetwork/server-storage/vm/documentation/dbrac112040-ovm-tmplt-prod-config-1979320.pdf" for production, the Readme in the download pages is very helpful as well.
You could use Oracle VM VirtualBox as well "Oracle VM VirtualBox - Downloads | Oracle Technology Network | Oracle", wich you can install in Windows and is very easy to use, although I think there's no template for 11.2 RAC and you should convert the VM templates like in vmware. There's a link on how to use VM templates in Virtualbox "Build an 11gR2 RAC Cluster in VirtualBox Using OVM Templates"
As for #2, the downloaded file might be corrupted, you can try to check the md5 or so to see if the download is ok or not ( press on "View Digest" on the download page ).
You have to be more specific.
There are thousands of os errors.
What exact error did you encounter
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