I am a law school graduate. What I offer is mere information, not to be construed as forming an attorney client relationship.
Warrants don't expire. Not like milk. Basically, if it is years and years and years, the charges can be dismissed at the pre-trial phase based on a statute of limitations violation. But this statute of limitations depends on the state and the crime.
As for warrants --> you can hire an attorney to inquire for you. You can hire a private investigator to run a search. Sometimes the local sheriff's department or police department have their warrants posted online.