Onion planting questions?

I know this is a gardening question, but I tend to get more answers from the V&V section. These questions may make me sound stupid, but bare with me.
1.) When I plant an onion seed, does it produce 1 onion or many onions?
2.) Are my scallion seeds and my onion seeds the [...]

I want scallion seeds for spring planting.?

ohio area so by may 15

Planting Herbs With Vegetables Repels Insect Pests

PLANTING HERBS WITH VEGETABLES REPELS INSECT PESTS 
Planting herbs together with vegetables would reduce your production cost while increases your yield. 
Another term used in this method is called companion cropping or companion planting. It is an intercropping technique which involves planting two or more plants in one area for controlling pest attack. 
The plant species planted together [...]