MCS is Michigan Competitive Scholarship. Basically anyone admitted by UMich should have met the required academic criteria. You need to provide the SSN by phone or at the website to enter. It is easier to do it on the web. Once you have the account set up, you can set the primary in state college or they can get that from your FAFSA also. If you applied to more than one Michigan public college, just make sure it is the right one you planned to enroll on their site. Depending on the college and FAFSA data, it will show your eligibility to the MCS and the other fund with expected amount. The MCS has been increased from below $700 to up to $1000 last year.
The EA admission data is hard to find. Around 30-40% of total admission is from EA in recent years. Around 1/3 of total admission is from in state, but I think the ratio may be higher for EA. So I am expecting at least 2000 in state students have been accepted and that include most if not all the Regent Scholarship recipients.