Legal Question in Real Estate Law in California

Your starting point would be to prepare and take to the clerk a Request for Entry of Default on Judicial Council Form CIV-100. This form also allows you to request entry of judgment, but you'll need to decide whether under the facts of your case a clerk's judgment would give you what you need, or whether to apply for a judge's judgment. If you thought you needed a TRO, maybe a clerk's judgment is inadequate. Also, the clerk may question your entitlement to a judgment, due to the lack of a returned summons -- the notion that a submission of an opposition is a sufficient "appearance" to give the court jurisdiction over the defendant may be beyond the clerk's knowledge or authority to decide. I'd sure try to get default entered, but I can't say how far you'll get, with the unusual deviation from prescribed summons-service procedure.

No. Appearing in response to a TRO is a "special appearance" and does not give the court general jurisdiction over the person. You must serve the summons.

You cannot take the default of someone who has not been served with a summons. Sneaking around as Mr. Whipple suggests is bound to get you in trouble and be a big waste of your time.