Yes all your degrees, mark sheet and certificates along with your ECA report will stay in one folder only and you can attached your IELTS too that's fine.
About your nomination certificate, it is not required as the Province would have sent to CIC already and that is exactly what they mention in their email when they nominate you that they have informed CIC that they would like to nominate you. So no need to attach your nomination certificate, CIC already knows about it.
Please remember one thing, Do not attach anything that CIC has never asked for, that will only result in increasing their work since they will not consider those additional documents and that will not even get you any additional points. Only provide what they have asked in order to make it simple and clear to them.
Good luck