When one asserts they signed a mediation agreement out of duress, they are really alluding to the idea that a mediation agreement is first and foremost, a contract. A mediation agreement therefore, needs to follow rules of basic contract construction in order to be valid. In that vein, mediation agreements can be subject to invalidation by an aggrieved party due to duress, coercion, or perhaps even lack of informed consent by the aggrieved signing party.
That is the good news for someone...
One would want to make sure they accomplished their goals of service, not getting a response, getting a default judgment on the record, possibly "proving it up" at a later hearing, etc. while being mindful of the statute of limitations (aka the time limit you're allowed to file lawsuit within). In California, very generally speaking, you have two years from the date of injury to file.
Visit with a local experienced immigration attorney who can help you put forth the best evidence to help you with your application. DACA is a one-shot deal so you don't want to send it and think "oh, I could have made my application stronger!"
Anyone can participate in mediation as it is a voluntary process. Anyone can refuse to participate in it also however, unless court ordered, and even then, if one really doesn't want to, the mediator may have to stop the mediation, even if court ordered. You should determine if there are any contested issues, and what they are, then talk to an attorney or mediator to see how they can help you reach your specific goals.
The stay won't exist after the bankruptcy case is dismissed. There won't be a penalty for filing a bankruptcy and not following through - you received temporary protection - keep in mind you may not be able to file another bankruptcy for a period of 180 days due to this one not being completed - please check with a Bankruptcy attorney.
It appears you stopped payment on a check to a contractor for a service charge. You made an agreement then his agents came to your house with an estimate - but did not do the job. It seems like you did not pay for the service of them coming to make an estimate like you said you would, and they did give you an estimate so you may owe the contractor. If you did agree for them to come to give you an estimate, that may be all that you agreed to so you should have paid. You did not also agree to...
You still qualify, and if you are 20 years old, you are an adult, and could meet with an attorney to arrange putting your application together. It would be wise to obtain your record so ensure there are no errors as they are common on background checks.