I don't recall the volume, but you can use a standard cylinder volume calculator on google. Its for tank volume, but just think of your loop as a really long tank that is only 3/4" tall.
The antifreeze used said to mix 50/50 for -10F pumping. It went lower than this for freeze protection and lower yet for burst protection. The antifreeze is Cryo-Tek 100 Anti-Freeze, 5 Gallon from supplyhouse.com for $64.95. If you buy more than one, then it even ships for free. UPS delivered to me next day, very well packaged.