Your ramble is a bit confusing. But you question of whether 1381 demands apply to both misdemeanors and felonies - the answer is yes. A demand to be brought to court and face charges via a 1381 demand applies to both misdemeanors and felonies.
The above information does not establish an attorney client relationship nor is it meant to provide legal advice.
A 1381 Demand applies to both felonies and misdemeanors.
Your public defender told you the wrong thing.
A 1381 Demand, once filed, obligates the prosecution to remove you to local custody within 90 days to answer to the charges.
If the prosecution fails to do so, a Sixth Amendment issue arises, in that you were arguably denied the right to a speedy trial.
Depending on the overall delay in having you brought to answer the charges, you may have a "Speedy Trial" motion to file to have the charges dismissed for the government's depriving you of your right to a speedy trial. The cases that are most often cited on this issue are People v. Serna and Barker v. Wingo.
The short answer is yes. If you have pending charges the demand results requires that your matter be prosecuted. Failure by the DA to prosecute your case may result in dismissal.