Almost all J seats take up more square footage than 2 Y seats. It varies a lot by airline. Also weight is more of a cost factor than space; the more complex J seats weigh hundreds of pounds. F seats can be equal to as many as 10 Y seats (e.g. the new CX F suite).

As for catering costs, these are easily found on the web (try google!). What airlines spend for meals varies tremendously, but most US airlines spend USD 35 to 50 for trans-Atlantic F/J flights, while the top airlines such as CX and SQ spend over USD 150 for F catering. They also use wines costing over USD 100 per bottle. I would guess the top-end food/wine cost runs about USD 400 per flight, while the bottom end (US Y catering) is about USD 10. Or about 40:1 ratio.