Few items.... I hit 8 feet deep this morning!

First question, when is the very earliest I can get fat head minnows in the water? How may should I purchase for 3/4 acre pond?

Second question, how would a pile of old tires all cabled together work for some underground structure? Could the minnows lay eggs on them like wood pallets? Seems like tires would be good to not get snagged on and good to swim around and easy to get out if I need to remove the for any reason if they are all cabled together in a ball or other weird shape.