It very much depends on the unit, but as everyone else has said, take what makes you comfortable.
Most emergency first-time admissions generally only last a few days unless there is reason to keep the person longer. The more often you go within a short period or time, the longer they tend to keep you. If you are headed to a specialized hospital or unit, you or your clinician came call and ask about this stuff.

The loafers and pants should be fine, and you are correct that most places will not allow a belt. If a jacket or sport coat is what you are comfortable in, take that, but also take a sweater (no long strings) in case they are sticklers about "no outer wear" and not understanding that the jacket or coat is a comfortable thing.

Oh, don't take your whole supply of meds, but know that they will not even consider looking at it unless it's in the original pharmacy container. Most units in general hospitals will supply meds from their own pharmacy, but some specialized hospitals need you to bring your own.

Good luck. <3