My first dove shoot - what to expect?

Here's the "True Word" from the Master himself: How many cartridges will the reputed "top shot" require to bag today's Federal limit of 12 to 15 doves? Anytime you can kill 15 doves with a carton of hulls (I assume Nash meant 25) you have just about run competition ragged. With a 50% average you can walk out of any dove field with your head high"!!

Just curious, living in a "No Kill" dove State (we raise 'em for our pals down in Dixie, y'all be's welcomed)-- how the one dove for 8 shells stats came about.
Comparing mourning (or in your case, Sir- afternoon doves) to mallards zipping down the river in late October or even bluebills and ringbills straffing the long string of blocks on lake Ferschullinger in mid-Nov is like comparing a fire hydrant to a 155 field gun) BUT if I only averaged one dead mallard for every eight shells (and at the high price of non-toxic shot today) I'd give it up and learn to love golf more- WOW

Do you have to use steel shot in legal dove States, as they are migratory. If I wanted to use my "Slim Boggins" 20 bore on a dove shoot (the 20 M12 my Dad and Grandfather gave me on my 11th. birthday) does it have to have a 3 shot plug?