I am going to answer here in case someone else needs the info in the future.
1. The taskbar is dark because the image you are using is very transparent. When your looking at it in the preview it has a light background so it makes the taskbar look lighter. If you make your image less transparent you will see that the actual color of the taskbar is alot closer to dark blue than light blue. You have a dark wallpaper and thats why the taskbar is so dark.
2. Your start button image is 65 pixles high. The preview will show the enitre button but when the skin is applied the taskbar height is set based on the content margins of most of the taskbar functions. In other words, the start button image is getting cut off because the taskbar is not stretching in height enough. It works pretty good if you adjust your taskbar to double height.
There are a couple of ways to handle the problem.
- You can make an oversized start button. See my Kali wb skin to see how it is done.
WWW Link It will take some rewoking of your image though.
- Adjust your sizing margins and content margins to match the start button and keep
it at double height. With the size of the start button as is, you will end up with a double
height taskbar anyways, because the start button is so big. As is, you won't get the taskbar
to match at single height.
- Remake the start button smaller so it cooperates better. Also leave the girlie image without
background so you don't run into stretching problems trying to match the taskbar.
Hope some of this helps. Feel free to ask for help as you go.

* The skin looks to be a fun one.