A notice of levy does not have to specify what assets will be levied. If they actual do levy any assets it will likely be a bank account. You should probably contact the IRS and make some arrangements with them to forestall an actual levy.
They do not. I would prepare and file a Request for a Collection or Due Process Hearing (IRS Form 12153).
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The notice of intent to levy need not specify specific assets. The IRS can seize what it finds. The IRS will not seize exempt assets. The IRS will let you know what assets were taken. You should hire a competent tax lawyer in St. Louis.