Currently the MW tool will apply the patch to each separate node defined - CP, APPS, etc. Are you using a shared appltop environment? If so the MW has a workaround so that the patch only gets applied once as designed for shared appltop environments.
Not 100% sure on the RAC - there is nothing in the setup that includes a RAC configuration. Since almost all of the processes occur on the apps nodes I don't see why it wouldn't work. You would most likely have to perform the database steps manually - like autoconfig on the database tier and other steps like that.
Would you like to be a test bed for RAC and we can take your feedback and add enhancements to the product where necessary?