Engineer Life Cycle

Hi guys, I had to set up a new profile old one was 'Bellalikesalien'; Bella is my pet dog.... I have pondered of the life cycle or reproduction of the Engineer / Space Jockey and in seperate posts the tail of the facehugger / the trunk of the Engineer / and the contents that David is pulling out of the Urn have all been compared for their similarities. I am going to suggest a few of my thoughts and would be grateful if people would like to discuss these with me. 1. The Engineer's are pretty much in trouble because they have exhisted for so long and need fresh DNA in order to propagate their species. They use planets to create life in order to preserve their own; not really having any empathy for the lives they are creating. 2. The Ampules contain infant Engineer's, I believe these will be face hugger like organisms. I wander what would happen if a face hugger was not to impregnate someone and would be left to age and grow. Would it die? or would it grow into something else? An engineer perhaps? 3. The infant Engineer (facehugger) when threatened could become the ultimate weapon. Attaching it's self to the threat, becoming the Alien and then wiping out all other potential threats. But creating more egg's and infant Engineer's, thus propogating the species. 4. Or perhaps the natural evolution of the Engineer is ... Egg... Facehugger... Chestbuster... Xeno... Engineer... The xeno sheads it's skid! There are similarities, are these creatures all one in the same? Just at different stages of the organisms life cycle? 5. As the Engineer is perhaps infertile perhaps fresh DNA; i.e. human DNA is required in order to save a dying race? I would wecome any comments or ideas Thank You :)