Definitely keep the elyrium, you'll need it to research and upgrade your equipment in the late game. Titan armour, ghost armour, firestorms etc will drain your elyrium stocks significantly.
Will do. I don't really plan ahead tbh(its just the way I play games) so have no idea about research trees, even though I have played the game many times!
Got a race on in my current game....Russia and UK both at max panic, council report in 15 days, just started work on a satellite uplink which will take 14 days!