Hi
The following answer is based on ISO-14001:
1. There is no specific level (I assume that you are referring to Senior Management, Middle Management, Junior Management etc.) prescribed in the standard for a Management Representative. The requirement is that the "TOP MANAGEMENT" appoints the Management Representative. He/She should have access to the top management to support the review process
2. The standard says: "top management shall appoint (a) specific Management Representative(s)"; the (s) at the end of the quote indicates that there can be more than one Management Representative.
In practice, I have seen that senior managers are appointed as Management Representatives in most of the organizations. This helps the coordination better.
As for the position of the Management Representative in the organization chart, it depends on his/her other responsibilities within the organization. It is possible that the Management Representative has a dotted line relationship with the top management.
With kind regards,
Ramakrishnan