What is Bitcoin?

Bitcoin is a cryptocurrency, which was 1st introduced October 31st 2008,
by an unidentified programmer / group of programmers, although many have come forth and tried to claim credit.

What is the Bitcoin Difficulty at now?

Take a look at Bitcoinwisdom's Difficulty chart

What is the current Bitcoin reward per block?

This wiki page on Controlled Supply Information

What is Bitcoin Cash?

Bitcoin Cash ( BCH ) is a version of Bitcoin after the fork occurred