*Roth 401k over multiple years, $4000. *lost job *Rolling it over to Roth IRA (backdoor, allowing me to go over 5500 limit) *Would I have to pay taxes on the $4000?

It depends on who contributed the $4000.  If this is the amount you contributed to a Roth 401K, you wouldn't have to pay taxes on the $4000 that you contributed, because, since you are making a Roth-to-Roth rollover, you have already paid the taxes on this contribution.  However, if you are rolling over company matches and earnings, that is another story.  Your company matches and earnings are not in a Roth, but rather considered in a Traditional 401K.  So if you roll these over to a Roth IRA, you will pay tax on the distribution, because you are changing the status of the deductions from deductible from income and tax-deferred growth to a taxable distribution and tax-exempt growth.  

Please click on this link to see the IRS' answer to the question:  Can my employer match my designated Roth contributions? Must my employer allocate the matching contributions to a designated Roth account?

Thank you. So it is either all or nothing? Does this get split to show my direct contributions vs company/earnings?

You might get two 1099-Rs.  One will be coded as a Roth rollover, and the other may have a code 2 in box 7.  If you have this, this would be the taxable amount.  When you roll-over this amount, it is converted, and you elect to include it as taxable income in this year's return whereas it was not counted as taxable income before.