I can't remember it being written anywhere which one is longer than the other.

Complex topics take longer than difficult ones. As an example here's the following:

 

Alien biology appears as "Difficult" and has a timetodevelop of 23

Life support appears as "Complex" and has a timetodevelop of 91

Complex topics take longer than difficult ones. As an example here's the following:

 

Alien biology appears as "Difficult" and has a timetodevelop of 23

Life support appears as "Complex" and has a timetodevelop of 91

 

Where do you find that information? I DL'ed the game from Steam and I'm under the impression I missed a whole crap load of info..... (no instruction book)

The info was obtained by extracting the contents of the gamedata.vfs file with one of the vfs tools available at the files section. The exact file is {gamedata.vfs}\game\configs\strategic\research\technology.txt

 

For the manual, check where the game's installed (have no idea were Steam keeps them) and check if there's a pdf file there. Don't expect an extensive manual.