This part depends on how frequently you fly and fly SWA. WGA don't come with refundable fare but your money isn't all lost either. You'd get a voucher valid for 1 year from booking date (not flying date) that can be used.
Yes you would be but I'll have to disagree with the other person's comment regarding how many people are on the plane. Pre-boards are 1 aspect but so are connecting flights. On flights where you are the connection point people are already on the plane. All that said I wouldn't purchase EBCI and Business Select. I would just do Business Select if you are considering it (for us the cost difference between WGA and Business Select is usually too much). Also keep in mind if there is any slots left from A1-A15 at the gate you can pay for Upgraded Boarded which fills in those leftover spots.