I think you're asking whether you have, not whether you can. And the answer is no, you don't have to continue working while your COS application is pending. As long as you were in status (i.e., working) at the time of filing, you are authorized to remain in the U.S. and wait for a decision on the COS application.
Assuming she is otherwise eligible for permanent residence, and also assuming you're a U.S. citizen, she will be able to apply for adjustment of status based on the I-130 Petition that you will be filing for her as your wife. Yes, you'll money on the plane ticket, but the filing fees are a bit more, plus you really should consider hiring a good immigration attorney.
My colleagues are correct - K3 doesn't make sense anymore. What seems strange is the length of time your I-130 Petition has been pending. You should have heard from USCIS by now. Have you checked the status of your I-130 petition on their website (www.uscis.gov)?
Gregory Romanovsky, Esq.
12 Marshall Street
Boston, MA 02108
If he wants to keep his permanent resident status, he should definitely contest it. He will have a decent chance in the Boston Immigration Court, assuming he has been maintaining ties to the U.S. Talk to an experienced immigration attorney.
The answer depends on the timing of your N-400 and your level of comfort in having your family here without authorization. If you've already filed for naturalization and you're in the Boston area, chances are you will be called in for an interview fairly soon (if you haven't been already). It WILL be possible to adjust their status even if they're no longer in status by the time you naturalize (and any period of unlawful presence will be forgiven, provided they don't leave the U.S. before you...