headingwest:
Is it correct that when you include a library, it sits in flash and reduces overall available space?
I want to consider SoftwareSerial and also TinyWire - how do I calculate how much space they will take up in flash??
All your code goes into flash, library or not.
Is there a list of libraries and compiled sizes anywhere?
It would vary by processor, and also adding two libraries almost certainly would use less combined space than each one alone. This is because they are likely to share functions (eg. floating point maths). So you can't just add up the figures for each library and get a total.
Even adding a library, the memory used depends on whether you use all its features. Example:
void setup ()
{
Serial.begin (115200);
} // end of setup
void loop () { }
Compiles (for the Uno) to 1,744 bytes.
Now add one line (from the same library):
void setup ()
{
Serial.begin (115200);
Serial.flush ();
} // end of setup
void loop () { }
Now it compiles to 1,760 bytes.
Add another couple of lines:
void setup ()
{
Serial.begin (115200);
Serial.flush ();
if (Serial.available ())
Serial.print (Serial.read ());
} // end of setup
void loop () { }
Now 2,270 bytes.
And that is all from the HardwareSerial library.
So, there is no easy answer. Try it and see.