If they determine I should indeed be classified as W-2, will I owe the former employer money back? =>>>>you can talk to your employer about it first, and let them know that you have serious concerns. If they are not willing to cooperate then you should contact the IRS directly to let them know about your personal situation. In general, if you're doing the same job for the same company as before under the same working conditions, then your employer can not wave his magic wand and make you a contract worker to save himself the payroll taxes. Does not matter one whit if you're an hourly or salaried employee. There are some very severe consequences that can come with employers classifying employees as independent contractors when they are actually W-2 workers.
How will my taxes be determined and how long does it take? =>>>>>>you need to settle down your situation first with your ER or IRS.I guess they ‘d let you know
Should I just go ahead and file as 1099 until I hear from IRS, otherwise?=>>>>>>> IN MY OPINION, PLEASE OCNTACT THE irs FIRST, THEN
You MAY/NEED TO file a form SS-8, as you said, (You can ask the IRS to make a determination on your employee status by submitting a form SS-8)with the IRS. You file a 1040 with a form 8919. If you are an employee and your employer is doing this to avoid paying payroll taxes and unemployment insurance they'll be informed/instructed to pay you as an employee. but I guess, your problem with the employer is broader than this.
Should I just ask the former employer for a W-2? =>>>>>the fact that you were issued the 1099-MISC instead of W2, then, you are being treated as a independent contractor , NOT a regular employee but a self employed taxpayer filing Sch C of 1040.
In which case would they require me to pay them back taxes=>>>>aslongas you get paid by your employer Imean as you received taxable income, yes.unless you pay taxes to IRS/state by the due date then yes. So you need to p[ay taxes first to IRS/state.