How does my spouse add points? Do their IELTS and ECA help?

Yes, both can help. When your spouse comes with you, the CRS awards points for their first official language results, their education (which needs an ECA if it's foreign), and any Canadian work experience they have. These spouse factors can add a meaningful number of points, sometimes enough to offset the different points split for couples. If your spouse hasn't taken a language test yet, that's often the easiest extra points available to your family.