Explore and loot, i've barely touched the main quest and I have two, maybe three left. --- Dark sorcerer, king of dark intentions, sensual pleasures pirate, constant hankering for honey, sprinkly toes thrillseeker extraordinaire.
For Seeker Tokens you find them randomly in treasure chests, very annoying quest, although i believe you can also have some forgeries in there and still have it count? The same for War Bugles, although those are easier since you can limit yourself to just doing a sweep of the city and then resting.
Geo Saurians spoilers below
They are the final upgrades to Saurians that you run into found only in the Tainted Mountains, which you don't go to until the end of the game.