Hi, Lubi.
Nice to see you back again for a second tour.
Go to Appearance > Design Settings > Edit All Default Design Settings and add the following style to your Custom CSS box:
.slideMenu ul li a,
.slideMenu ul li ul li a,
.slideMenu ul li.current-menu-item ul li a,
.slideMenu ul li.current-menu-ancestor ul li a,
.slideMenu ul li ul li.current-menu-item a,
.slideMenu ul li ul li.current-menu-item ul li a,
.noShowcaseContent.noHeaderContent .slideMenu ul li.current-menu-item ul li a,
.noShowcaseContent.noHeaderContent .slideMenu ul li.current-menu-ancestor ul li a,
.noShowcaseContent.noHeaderContent .slideMenu ul li ul li.current-menu-ancestor a,
.noShowcaseContent.noHeaderContent .slideMenu ul li ul li.current-menu-ancestor li a {
text-shadow: none !important
}
I think that should disable text shadows in the navigation menu. Depending on the number of levels of sub-menu that you have you may or may not need to add more selectors to that list.
If you use the Internet Explorer, Chrome or Safari browsers you can use their built-in developer tools to point at and “inspect” elements on a web page to find out what styles they use. You can even tweak the styles live to experiment with any changes you might fancy. If you use Firefox then there is an add-on named Firebug you can install which gives that browser the same functionality as the developer tools built into the other browsers.
With regard to your supplemental question, I am going to ask you to please start a new topic for each separate issue that you have. It helps everybody if we can keep topics tightly focussed on single issues. No big deal, but people searching the forum for help will be able to find that help more quickly if each topic discusses just a single issue. 
