Frequency Counter using Arduino Uno

I'm new to the Arduino and would like to build the Frequency Counter using Arduino (…) which is a great project but I have a few questions:

1 - For the LCD panel the article refers to a related article "Interfacing 16x2 LCD with Arduino (…) which shows the LCD part number as: JHD_162ALCD;  I'm in the USA, and I have not been able to source this part at all.  Can anyone provide a source for the part or an alternative equivalent part that would work?  If you can, please provide source name/website and part number.

2 - The first line n the sketch for the Frequency Counter project shows an #include that references "LiquidCrystal.h":  #include <LiquidCrystal.h>

Is the LiquidCrystal.h part of the Arduino IDE or is it a file I have to source from elsewhere?  Can you provide specifics, i.e. where to get the file?  Is that file specific to the JHD_162ALCD LCD or is it required for any LCD?  

Thanks for any assistance!