Hey congrats! I am going to be following along closely as I just got the exact same tank setup and cycling a few weeks back. Hate that you had the issue with the shipping like that. Mine came without the wood pallet - but did have the cardboard bottom section. Thankfully the fedex freight guy helped me break the pieces down in my front yard and carry the individual boxes up the stairs to my porch.
The instructions are a joke. I didn't break the fasteners, but I did over tighten the screws that hold the door hinges. That resulted in very noticeable and annoying dimples on the front door where the hinges attach. I also have an extra gray bracket piece that is about 8 inches long and looks like it goes in the sump that wasn't shown in the instructions.
Sorry I missed this the other day. I’m working from home tomorrow and can help you. The only thing I can’t help with is what the stupid grey thing is for. I was thinking a prove holder that’s missing the bracket maybe?!