1. The pins can go in either way. Makes no difference.
2. The trigger pin comes out first and goes back in first. After the trigger pin is installed, the slide lock lever goes in next. Its spring is tensioned under the trigger pin. Then, the narrower locking block pin goes in. If the slide lock spring is in the way, jiggle the slide lock lever until you can push the locking pin in.
Not aware of any diagrams that show the sequence, but the YouTube vids should get you through it.
"I don't give a damn for a man that can only spell a word one way." — Mark Twain