I have been living in Zurich since ~2.5 years with my family. My wife and child are EU citizens, while I am a non-EU citizen. I recently lost my job and am living here as a dependent of my wife. My spouse has got a "job search" L permit. Now if my spouse finds a short term job for 6 months, will she get an L permit? I heard one can get a B permit after staying here for 2 years. What kind of permit will I get? Will I be able to work with that permit? I have been facing immense difficulty in finding a job here without a work permit despite high qualifications and experience. I look forward to your valued response which will be highly appreciated.

Yes, she will get an L permit. B's are only given for contracts that are longer than a year. You would get the same type of permit. Not sure if you could work with that without authorisation, but if you can it would only be for the length of your wife's contract since she would end up back on a job seeker's again after the contract ended so you wouldn't be able to continue working unless your employer applied for an independent permit for you under the non-EU hiring criteria.

You heard wrong. What it probably references is that most non-EU nationals who are main permit holders as you were will start on an L permit and be on that for 2 years before they might get a B at the next renewal date. But that isn't always the case and is not tied to how long you're here.