New player trying to get into MP

As a new player MP seems really overwhelming, so I would like to ask for some advice.

1. I tried looking at some build orders, and so far I'm a little overwhelmed by the endless amount of combinations of civ+map+strategy. The main build order i'm super comfortable with is fast castle into castle drop. Which works against the AI, but I assume is hot garbage against any human player. I practiced other builds a bit with the AI and archers are too cheesy for them and they deal with scouts decently well with spears. If someone can give me a suggested civ+build order for each of the eight map in ranked pools I would be super grateful.
2. I want to practice in casual but it's either NOOBS ONLY or NO NOOBS, I don't know if beating extreme AI without cheesing too much is considered a noob or not, since the few friends I play with can't beat hard AI on their own yet. So I can't join either of the games in fear of public shaming.
3. Any advice is appreciated, thank you in advance!