Since "The law mandates that trains blow 2 short and 1 long when approaching any crossing for safety of the public, and regardless of the hour", I am wondering why on October 11 at 4:00 a.m. I counted over 20 horn blows. This happens frequently.

Lets use some simple logic here. You have a horn sequence that consists of 4 distinct sounds. Now, you have 5 consecutive crossings in a relatively short span of track and the train is traveling around 49 mph. I'll let you figure the rest out.

Depending on where you live you could be between BNSF and Union Pacific. Some night have heavier trains than others. If it seemed like it was only one train than you should figure out which company it was and contact them directly. Also try to get the lead engine number along with time and date.