Thanos,
DVD Studio Pro as its name suggests is a professional application (although due to Apple's and the late Mr. Jobs' eforts it tends to be more Pro-Sumer application). As such it does not allow many shortcuts in creating DVDs.
In my experirence, the fastest way to create a good looking and fully functional menu is Photoshop/Motion (AfterEffects) combination.
Alex Asp/Solaris Digital Ltd.
Subtitle utilities
HERE
Anti-aliasing for Highlights and Subtitles:
HERE