What are the benefits of having Tricare Prime for my spouse?

Your buddy is an idiot, don't listen to junior enlisted for life and career advice.

You and your spouse should already be enrolled in Tricare Prime. Unless you specifically changed your spouse's enrollment she is enrolled in Prime.

Which Tricare you're enrolled in makes no difference to the EFMP screening. An Army doctor is required to do the screening

Lower out-of-pocket costs.

First, don’t trust barracks lawyers. Your buddy doesn’t have a clue.

Second, if your wife is already in deers and added as a dependent she should already be added at Tricare Prime as a default. Dont hesitate to stop by your nearest tricare rep to go over the differences of the various Tricare levels.

Third, Screenings don’t depend on your Tricare level. It’s covered regardless

Fourth,
If you can afford elevating your Tricare level you should. It’s worth it