Squash should be picked when they have turned to the ripe colour, (beigy orange) They can grow to any size but usually about 8" long. They are pear shaped and yes there are seeds inside that are removed when cooking. If I remember correctly Hunter is an f1 seed. Not suitable for collecting to grow the same plant again.

To help with the ripening you should remove any leaves that cover the Squash.

Tap them with your knuckles and if you get a 'thud' they are not ready,if they sound a bit hollow then they are ready for harvesting!

Not 100% accurate but it is a guide!