Hello Johannes,
I will make one suggestion about music, but I think it is not insignificant. I think trying to replicate the sounds of an orchestra digitally is bound to limit the possible quality. The English ecclesiastical architect and artist A. W. N. Pugin, a champion of the true Gothic revival, held that the manner with which one produces a piece of art should conform to the materials. Wood should be used like wood, not like stone; metals should be used in accordance with their nature. A second principle of his was to base the ornamentation upon the structure rather than have it disguise the structure. Since Excalibur is already impressive in terms of graphical and game content, the music has to be equally impressive. But without a budget, this is very difficult. Try to use your electronic instruments in accordance with their capabilities, inspired, obviously by Star Trek's orchestral legacy, but not a slave to it. You might find some inspiration in Messiaen's use of the ondes martinot (Turangalila), or even transcriptions of Bach's work for electronic instruments.
As for Giacchino, I think his lost work was excellent, especially for tv, but his ST2009 score I found a little thin. As a video game composer I think he learned how to get mileage out of a theme, but his use of a full orchestra is a little one dimensional.
Best of luck!
