I bought my grapes earlier

My old-skool recipe calls for:
* 3 ½ lb. green grapes
* 1 lb. black grape
* 6 Pints of boiling water
* ....
It doesn't say how much it makes though, it's close to 1 gallon (4.5 Litres), so I assume this is what it'll yield? Does it sound about right to you giving the quantities of the grape. Cheers
Also, it suggests to add all the ingredients (including yeast etc) and let sit for 10 days covered with towel. Then after 10 days, strain into a demi-john with an airlock and ferment until finished.
This kinda confuses me. I would of thought the yeast would be added after straining into the demi-john... Nevertheless, I will follow the book, just want to know your thoughts on this method, I believe the book is half century old.
Thank You