Front bumper bolt confusion.. why so many?

I've removed my front bumper a few times but it's been years so I forget where everything goes, and I'm in the slow process of doing the 2.5 conversion. I pulled off the old bumper yesterday and when doing so I realize there are at least three different types of bolts that hold the front on. There are thicker black ones, thicker silver, thin black and then silver bolts/screws.

The online diagrams I see are pretty useless. All of the bolts are extremely similar in size but I know things don't like to line up perfectly if they get switched around.
Does anyone recall which screws go where?

Side note: are all of the plastic push pins on the front bumper the same? I know there are three on top and two on the bottom but I think they are different sizes.