Howdo.... Baffle is attached to both the top shell and the bottom shell. It allows the down to loft up and creat a uniformed thickness across the entire quilt. Most summer quilts can be sewn through, no baffle, 3 season usually has about 1 1/2 to 2" baffles and winter around 3 1/2 to 4".
I personally would make the quilt 6" long than you height, as for width that would depend on your waistline and shoulder line...
Amount of down is easy, figure area in inches of quilt multiply by desired thickness. Divide by fp of down and then multiply by 1.15 for 15% overfill of 1.2 for 20%. Example
50X80 quilt is 4000 s.i.
4000 s.i. at 3" loft is 12000 c.i.
using 800FP down 12000/800 is 15 oz
15 oz X 1.15 17.25 oz of 800FP down needed...
Hope that helps...