1. This "logo in menu" is not really a part of imagevue in any way, os i cant provide much help on this subject. You can put a logo as part of your background image, but you must try to position it so that it doesnt overlap any other navigation items of course.
You should be able to use different size and color for some menu items, by using basic html tags in the title. For example:
<font size="15"><bold>title here</bold></font>
2. "mainmenu" is not valie for horizontal menu simply because the horizontal menu does not expand/collapse! Where would it be??
3. Sorry, what "writing" do you mean? There is a theme setting for opacity of menu item background for ACTIVE items. This should easily be enough for visitors to understand, and unfortunately you cant set active colors for menu items.
4. This is because you have been trying to set the alignment of imagecontrols to below image. This setting is intended for galleries that only use image-display, for example slideshow. Elsewise, the controls will try to attach below an image that doesnt exist, so it positions at 0!
5. Not sure what you mean. The startfolder is like any other folder in the gallery, unless you have set it to a filemod. You can remove the frame of the filemod in admin -> settings, under "filemod".
6. You can change the margin for texts in admin -> settings -> image.text.text[].margin