Possum board revisited

I have a McSpadden model SSWW made in 2003. SS stands for "sweet sound"! The company no longer sells this model but available as a kit. Their ready-made possum board is for the standard model and according to Jim Woods from McSpadden it will not help keep my model in position lengthwise. I read Robin-Clark's old posting here, it encouraged me and I decided to make my own. I do have a few questions:

1. Intend to use a piece of walnut 3/8 thick. is it strong enough? While my dulcimer is hourglass shaped, I will keep the board rectangular.

2. Will use home made dowels for stoppers. Would standard wood glue be strong enough to hold the instrument?

3. Does the board need a finish like Danish Oil or leaving plain is better?

4. The two sample pictures I saw show a protective layer at the stoppers. What material would protect the instrument, but won't muffle the sound?

5. I intend to add strap buttons to the board. Where they should be placed: On the side of the stoppers or on the board's surface?

Your replies are appreciated in advance.