We have not changed how shadows work, so they should be working as usual and they certainly do here.
The popup taskswitcher works perfectly with buttons 4 & 5 on a Microsoft mouse. If you are using logitech software you may need to remove it as it may be mapping those buttons to some other functions and thats why WFX is not able to see them.
I will look into the transparent windows issue.
Also please make sure your wfx.dll and wfxload.dll are dated May 2006 and that you are on XP 32 bit. The 64 bit wfx has not been updated yet.