Wedding dress progress

I draped the wedding dress fabrics over my dress form to get an impression how it might look later (and to motivate myself to sew the muslin).

Fabrics I have:

- 4 m of linen-silk satin, quite heavy with a nice drape, with one shiny and one dull side, and a bit of horizontal structure
- 3.5 m cotton-silk crepe chiffon with a vertical structure
- 0.5 m dull silk with shiny rhombs
- a piece of crumbled raw cotton with a more rustic look in the same shade of ivory white.

The pattern I want to use is burda 7572 but with a self drafted skirt (as a circle segment), because I do not want to cut gorgeous fabric into so many small pieces, one of my whims.





In the first picture I layered the rhomb silk and the satin for the top, the satin and the chiffon for the skirt, and used the crumbled cotton as a band in the empire waist.

In the second picture I used the shiny side of the satin for the top, the dull side for the underskirt, left the chiffon skirt open in the front, and used the rhomb silk as a band.

(The waterfall collar and the kimono-look are not intended, it is just because I did not cut the fabric yet so I could only drape it that way.)

Now I am thinking about several decisions about the design and I also have several technical questions.

Design:
1. should I use layers in the top or not
2. which fabric to use for the band
3. leave the overskirt open in the front or not
4. if so, shiny or dull side up of the underskirt?

Construction (also design-related);
5. I know how to sew an invisible zipper, but how do you insert a zipper when you have a transparent top layer? When I have lining fabric, I sew the zipper into the main fabric and hand-sew the lining to it, but that does not seem right here. Do I sew the zipper in both layers at the same time? If so, do I try to make two separate side seams below that?
6. Can and should I insert the zipper in the side seam instead of the back?
7. If I have a back zipper, can I make the overskirt from two pieces with a center back seam and the front open, and no side seam? Or would that not drape and look nice because then I have the straight grain at the side and diagonal in the front?
8. I only once made something from chiffon before and then I used a small zigzag for the hem (folded, zigzagged and then cut back the seam allowance), is that the best hem option here?
9. all fabrics can be machine-washed (gentle cycle) according to the online-shop, should I pre-wash or not?
10. Do I have to cut the chiffon overskirt bigger than the satin underskirt?