The bad news is that you didn't realize these study guides existed when you were doing your planning at the beginning of the year. The good news is that you don't have to buy the whole bundle anymore. The Unit 3 assessment is on the horizon, so why buy the bundle that includes Unit 2?
The Study Guides can either be used to study for the test or at the beginning of the unit as a pre-assessment. I use them as the 5th, 15th, 25th, and 35th Week Assessments (aka Mid Term) that is required at my school.
Since the Study Guides are directly aligned to the Standards, they can also be used as a diagnostic tool. I use them along with the Unit Progress Check Class Checklist from the Everyday Math Assessment Handbook. Since each question in the Study Guide (and subsequent End-of-Unit Assessment) correlates to a specific standard--and sometimes two specific standards--I can grade each student according to the standard, then use the Class Checklist to group according to strengths and weaknesses and apply support or enrichment accordingly.
The problems are identical to the ones that are on the Everyday Math 4 Unit Assessments, but with different values.