Considering that some epic feats have a req of 27 in a stat there doesn't seem to be a stat cap.
Rituals are broken up into categories based on their function: Binding, Creation, Deception, Divination, Exploration, Restoration, Scrying, Travel and Warding. You can copy down rituals in a ritual book only from other ritual books. Ritual scrolls do not have the entire ritual, instead one use of the ritual has been stored in the scroll.
Rituals included are:
Animal Messenger, Comprehend Language, Gentle Repose, Magic Mouth, Make Whole, Secret Page, Silence, Tenser’s Floating Disk, Endure Elements, Eye of Alarm, Water Walk, Detect Secret Doors, Arcane Lock, Enchant Magic Item, Hand of Fate, Knock, Travelers’ Feast, Brew Potion, Hallucinatory Item, Magic Circle, Commune with Nature, Cure Disease, Discern Lies, Disenchant Magic Item, Leomund’s Secret Chest, Phantom Steed, Sending, Speak with Dead, Linked Portal, Raise Dead, Remove Affliction, Water Breathing, Wizard’s Sight, Consult Mystic, Detect Object, Drawmij’s Instant, Hallucinatory, Passwall, Shadow Walk, Eye of Warning, View Location, Consult Oracle, Planar Portal, View Object, Forbiddance, Loremaster’s Bargain, Observe Creature, Voice of Fate, True Portal