Acronym Soup: ROFLWPIMP ?

Questions

Who was British Prime Minister on Sunday 3rd September 1939?

Although the South American Anaconda is sometimes claimed to be the longest snake, this is actually the longest recorded snake?

The Top 10, The world's sleepiest mammals, at 12 hours or more per day?

This animal has the longest gestation period, at 660 days?

Insects and Spiders are the most abundant animal class. Which class holds the number two spot?