For the sake of consistency, please try to use the form "/ca". If you find older versions of things that use "_(ca)" we should move them to the new name. If you don't have sufficient rights to make such a move let me know and I'll do it for you.
Yes. You can delete "Template:Info/ca" file?
I would create "Template:Info_(ca)".
Thank you very much for your time
No, we should keep Template:Info/ca and delete Template:Info_(ca) because that is the old format.