Castile, Aragon, Almohads and Navarre get Las Navas Del Tosa or whatever it's called as a battle at the start of their campaign. Aragon as decisions can form the kingdom of spain (rename), foudn an empire (rename), ask the pope for money. Papal favor is hard to really tell, I think it's mainly lost by sacking a Christian city and gained by doing what the Pope asks. Crusades apparently do happen - people complained the Ayyubids fell to the hordes of Christians and I just saw Serbia on a boat with a full stack by Cyprus.
You'd need to check on either TWC or their discord what factions are considered more done than others. I'm not really seeing much decision/dilemma/unique mechanics for the Abbasids, I'd wager the Muslims in general lack the sort of thing you have with the Papacy. I am pretty sure I played with the trophy option (next to the wreath) on the campaign screen - judgment day. Prior to the april patch you had NATO in Europe. It might not be necessary to use judgment day anymore, but if you find it too lovey dovey among co-religionists try that.
By having my research at around 115-125% normal speed due to buildings I am probably 40 or so turns away from getting to T2/1300 units, and that was by taking a leisurely time in civilian. So around turn 120 or so I should have it.
The biggest issue is there's no mercenaries right now. If not for the arcane way of adding mercs (you have to edit the campaign map, meaning only one person can do it at a time) I'd have learned how to add mercs and offered to do it for them. If you want a similarly complete experience Ancient Empires I didn't play around with too long but it was spoiled for options on the campaign map. I wish they had taken AE's approach of "1 region per province" though, once you re-experience that you don't want to go back to the dumb current method CA likes.