A Plot Point campaign inspired by really early Perry Rhodan

As I am often gaming with groups that know nothing about the biggest German pulp scifi series, it would be great to play through the set up of the first cycle:

The PCs find an alien spaceship with incredible power (and some sick aliens) and it is left to them what do with it? Leave to space? Rule the Earth? Both!

Obviously it would be a sand box game, with a set up on Earth level (countries, military, economics and secret services) and one on galaxy level (a mighty decadent empire and different power groups in it that all want to take over Earth).

A proactive play style would be encouraged, but it would definitely be necessary to protect Earth - or to sell it out to the aliens?

Obiously while the basic ideas would be similar to Perry Rhodan, the window dressing would be different - especially the way the Aliens look. Maybe some transhuman elements would be fun, but that could already lead too far off.

Instead of finding the space ship on the moon (and restricting the PCs to beastronauts), the first adventure should be more like X-Files or Indiana Jones.

A potential place for the crashed space ship would be Northern China or Tibet. A question is if there should be Greys. And if it would make sense to have a Pirates/Ninjas/Robots/Monkeys aliens conception. And are Greys the fairy archetype? What other fantastic archetypes exist? Dwarves? Elves? Klingons? Are Orcs Monkeys? And what's with Zombies and Sharks? And Dinosaurs and Bears?

Also there should be a possibilty for characters to turn alien in the long run, without having to loose the inital character. Here the transhuman factor could come into play.

And don't forget the robot ruler!! ;)

Some research about real life alien esoterics could inspire me. Check here: http://en.wikipedia.org/wiki/List_of_alleged_UFO-related_extraterrestrials