Right now, I am as far in the Mage's Guild (College), as being part ways through 'Under Saarthal' where my next objective is to speak to the Arch Mage. I decided to do some radiant quests for the Orc in the Library. Can someone tell me do his radiant quests EVER STOP? Both his radiant book finding quests, along with Shalidor's Writings? This is getting quite monotonous. Am I even making progress for the guild?

By their very nature, most radiant quests never stop. That is the point of Radiant quests. You will always have something to do in Skyrim, even after you have finished Bethesda's hand-made quests.