anyone know if SO can purchase there ticket before they get visa

Can should be able to buy it but if something happens that they don't get the visa they are out the money. Usually you an get a 7 or 10 day advance ticket for ok money. I would wait being the type that hates to throw money away.

You can, but I wouldn't recommend it. ANYTHING can happen in this visa journey and it is always best to wait until you have your visa in hand.

I dont know of other airlines but british airway's one ways are flexiable for 50 dollars and they have up to a year to use it. If it gets near a year and still not able to use then you refund it minus 200.00.