If you are being audited, I would strongly encourage you to seek legal assistance. The examination process is meant to correct errors in the original filing: report all earned income; make appropriate classifications; and verify appropriate deductions/credits. After reclassification and application of available deductions, the net result may be that you overpaid tax (or underpaid resulting in a deficiency). If you overpaid, you may be entitled to a refund. Not all overpayments can be refunded though. If the overpayment was made more than three years ago, the statute of limitations has likely expired on your ability to recover that refund.
If you are not being audited and are simply considering amending your prior year returns, the same rule referenced above would apply to limit any potential refund. You do have the right to amend prior year returns to claim any potential refund you may be entitled to. Whether the reclassification alters your personal tax liability for prior years is something that would need to be analyzed after review and comparison with your returns as originally filed.
This answer is provided for informational purposes only, does not constitute legal advice, and does not create an attorney-client relationship. Actual legal advice can only be provided after completing a comprehensive consultation in which all of the relevant facts are discussed and reviewed.
I defer your tax question to Ms. Warrington since she is a Tax Attorney. However, from an employee stance, depending on your job duties, number of hours worked, etc., you may also be entitled to overtime wages if your employer misclassified you. Your employer may have misclassified you on purpose to avoid 1) taxes and 2) paying you overtime. Misclassification in wage/hour cases is very fact specific and it would be in your best interest to consult a labor and employment attorney that specializes in wage/hour cases. Good Luck!
I believe that you would be able to claim as a part of any damages the extra self-employment tax you paid to the IRS. Proving you were an employee as opposed to an independent contractor is very fact specific and no two cases are exactly alike. Therefore I suggest you seek further advice from a Florida employment and labor attorney.