Yeah it was a great show. Basically an 11 hour long movie broken up into 26 episodes. As continuity goes it doesn't get more gripping than this.
You are right about the ideas being re-used. Conan & Lana are basically prototypes for Pazu & Sheeta. The environmental theme is reused in Nausicaa (though the catastrophe has progressed far further - in Future Boy Conan it seems that the world can be saved, in Nausicaa it seems that there is no chance to reverse the condition), Monsley gets recycled as Princess Kushana in Nausicaa (more so in the manga, where it is clearer that she is quite a noble character. In the anime she is villain-ised to make the story work).