1-sewn! No seriously, just sew the insulation the to perimeter of your fabric leaving enough of a unsecured area(a hole) to later turn the quilt right-side out.
2-not too important, just as long as it is attached well. i use medium length stitches and i find no reason to change.
3-nope, thats the whole reason to go climashield vs primanloft, saves alot of work in construction
4-depends on your machine. My old machine would catch the insulation if it was on the bottom and the fabric was on top so i had to put the insulation on top and the fabric on bottom. IT works ok but is hard to see what you are doing with all the insulation fluffed up in the way. My current machine can sew with the insulation down and this makes it much easier as i can see where i am sewing on the fabric, also makes it much much easier to sew zippers and draw tubes as you can see them. Pin every 5" or so and hold all the materials in front and behind the needle. If you hold the material so the nylon is tight this will reduce(not eliminate) the insulation stretching. Just make sure that if it stretches you get it tacked back in place before you remove the next pin. This will keep the whole side from shifting on you.
Hope that helps, Troy got you going in the right direction