Learning new rituals is indeed rather slow (which I don't think is bad). My character is about 4 years in, and there are a fair number of rituals I know exist, but haven't been offered (including two of the spirit ones).
The only way I know of to get quests is to ask people how they are doing. You can occasionally get "lost character" quests in the wilderness by talking to woodsmen, but apart from that you get quests in villages.
Most quests in villages are "public", i.e. when talking to someone in that village they'll direct you to the quest giver, but some are private, i.e. revealed only if you happen to talk to that specific character.
Most quests give mundane rewards in the form of credits for goods (not animals!). Some give training (my second favorite type) in skills, some give spells (my favorite), some provide the location of a treasure, and a couple give specific rewards that seem to be essentially the same for every instance of that quest.