The obligation to return or destroy confidential information upon request (or at contract termination) is ubiquitous in confidentiality agreements. But in this era of distributed network computing and cloud storage, when nothing can ever be completely deleted everywhere, compliance with such a clause is illusory.
In US: must be an attorney licensed and in good standing in any state, territory or DC.
Outside US: must be a lawyer or equivalent (eg counselor, barrister, advocate, solicitor), duly educated and licensed/accredited and in good standing.
As a general rule, experienced and currently practicing lawyers, and those teaching law in the legal academy, are more likely to be admitted.