Ilum has 1 L, not two.

I did post in another thread, but i killed the world boss on Alderaan the other day, and he did NOT drop a white colour crystal, just two BoE prototypes and an epic schematic. I don't know if the schematic 'replaced' the colour crystal drop, but it seems fairly likely that all the 'rare' crystals aren't dropping any time soon. Perhaps an end-game only or a legacy feature for the rare colours?

Just to add something, me and a guildie dropped the world boss on Alderaan today, and he did NOT drop the white colour crystal - He dropped the two other epics that he was listed to drop on the DB sites, but not the colour crystal. Whether or not this is a case of he has a chance to drop it, i do not know, but it is looking more and more likely that these 'rare' colours are coming from end game content, unless anyone has a confirmed schematic drop from somewhere.

Whenever your mission window somehow closes (Like doing the things you said), there is a little tab at the top right of the screen, where your mission rewards will sit until you choose to accept them.