I've never found out what those removeable square (or round) pieces are on the fronts of cars these days. I've read they are for tie downs during transportation on traiins or boats, but I've removed mine and there is nothing behind them but the foam impact protection stuff.
What engine?
As far as the coolant leak, I don't know exactly why it's leaking, but I would start by checking and finding out where it's coming from. Hoses, expansion tank, water pump, etc.
Most likely your problem for what?
It is made of plastic. Repeated heat/cool cycles over time will eventually stress it wnough that it could crack and start leaking. I have seen a few crack.
I mod my other cars cause they are paid off....as long as I'm making payments on one, I dont sink money into it with many mods.The DJ is a good platform for it, I hope the aftermarket steps up. Such a sexy looking vehicle.