Pulling BOOT0 Pin Down

I was wondering if the resistor to pull down the BOOT0 pin is necessary for normal operation, assuming you want to boot from flash memory.

I would say yes.

See the Reference Manual for your part, which should be RM0091

http://www.st.com/resource/en/reference_manual/dm00031936.pdf

I was trying to find on the datasheet (STM32F0 series) to try and find more about the pin information but all I could find was the maximum allowed voltage on the pin.

ST uses to separate electrical data in the Datasheet, and 'logical' data (behavior of core & peripherals) into the Reference Manual.

Other vendors put all in one document.

You really want an external pull down so it doesn't float and have threshold conditions if the supply ramps slowly. Seen a bunch of posters with issues when they failed to do this.

To ensure stability on a finished product, yes, always add the pull-down resistor to the boot0 pin. 

If you are simply looking for a practical resistor value I suggest using a 100 K pull-down resistor.  This is the standard value I use with all of our designs and have never had an issue reported across a significant number of units.  Your mileage may vary.