AoE 2 openings

I am new to game, maybe not 0 but maybe 2, anyway what i am wondering is, are these openings must or not? I want to play with real people not with bots but i do not want to be cheesed or destroyed within 10-15 mins because i do not follow exact build guide.

also I was wondering, how important are shortcuts for buildings? should i try to learn them or build my own?

lastly, if anyone knows where i can find new or low rank players to play together?

thanks!