As far as decoys ~ One can be enough to then two or three. I like to mimic what I see real birds doing. For Fall I may use 6 to 10 or more as I do have quite an array of decoys.

For spring I like using 2 hens the most but do add a strutting Tom once and a while. But a Strutting Tom will make a less dominant Tom stay far out of gun range. So be aware of that.

My last spring hunt of this year I had a real nice MATURE TOM stay on the other side of the field and gobble his fool head off for over an hour easy. He clearly could see my twon hen decoys. One feeding and one laying ont he ground ready to be mated.
What he did not like was my simple real Jake fan I had mounted on a stick. No decoy body to this just a Jake Fan. And it kept Mr. Panzy 120 yards away!

Nothing I could do but just it there. As I was pinned......and this happens some times.!

JW