The Publication URI is available through the controller object which is available in the window.dialogArguments, so you should be able to use:

window.dialogArguments.controller.getItemPublicationUri()

Through the controller you can also get the actual item and related information, best to check it out in a debugger to see all available method.

isMultivalued is a method, so you should call it like: window.dialogArguments.getFields()[0].isMultivalued(), that should return you the correct value.

The Publication URI is available through the controller object which is available in the window.dialogArguments, so you should be able to use:

window.dialogArguments.controller.getItemPublicationUri()

Through the controller you can also get the actual item and related information, best to check it out in a debugger to see all available method.

isMultivalued is a method, so you should call it like: window.dialogArguments.getFields()[0].isMultivalued(), that should return you the correct value.

It's unclear to me why properties.fieldDefinition.localName does not work in IE. I have the same behaviour while it works fine in Chrome and FF (something you should report to Customer Support). For the time being, perhaps you can try to use window.dialogArguments.getFields()[0].getTypeName() instead, that does seem to return the fieldtype fine in both Chrome and IE for me.