Law regarding subpoenas.

My wife and I have been subpoenaed to testify in a custody battle. The divorced parties were our neighbors and at one time fairly close friends. In the course of our association that friendship has weakened and disappeared. I assume we are being summoned because our knowledge of their relationship and with regards to several verbal outbursts made by the woman towards my wife. We really, at this point in time want no further contact with either party. We’ve washed our hands of them, so to speak. My questions are as follows:
1) I assume we cannot ignore the subpoena. What are the consequences of doing so?
2) The trail is scheduled for 3 days. Who is responsible for time and wages lost during this fiasco?
3) Can the party that issued the subpoena be sued for lost time/wages?
4) Our son was recently (last week) diagnosed with type 1 diabetes and has his first appointment with the pediatric endocrinologist scheduled during this time frame. Can we get a medical exemption because we both need to be present at his appointment?
Thanks in advance for any advise.