Can I subpoena a witness whose testimony will demonstrate they were participant's in the crime rather than merely witnessing it?

Yes, you can subpoena any witnesses that will provide information relevant to your defense. However, the court has the power to appoint counsel...

Yes, the any government entity can be sued, including the Sheriff's Department. You have a choice of venue as well: You can sue in state court...

Can medical records be admissible as evidence when evidence code section 1101(a) is considered?

In California, character evidence is generally inadmissible in a civil case unless character evidence is an essential element of the case. ...