The bad news is that car insurance for an 18-year-old on their own separate policy is incredibly expensive — over $3,400 more than the national average. The good news? Typically, we see that combining insurance by adding your kid to your policy is the best route.
The owner of the trailer would need to add you to their policy if you will be pulling their trailer regularly. If you will not be pulling it regularly, you should be covered — but I recommend you check with your specific company for policy details to make sure. If you have any questions, don't hesitate to ask.
Typically, if the police are not involved, the accident will not show up on your motor vehicle report (MVR). However, the accident may show up as an at-fault accident on the CLUE report which is the report that pulls and verifies prior insurance claims.
The lookback for DUI is 10 years in Kansas. The other thing your husband would need to think about is if his job requires him to drive. As that would be a commercial policy, his DUI can be weighted more heavily than another job.
Unfortunately, fault can only be determined by claims adjuster personally assigned to the accident. However, for the other part of your question, because you were driving your company's vehicle on company time, if you were to be found at-fault then the company's insurance would take cover the damages.