Leaks, Oh the leaks (Rant and Question Enclosed)

[Purduegmc]

I started driving my truck more since I got new exhaust put on. I started to notice that I had an oil leak, I think I found the problem (the top bolts on the fuel pump were loose). Leak one found, I think.

Leak number 2.

I found that this new exhaust that the shop put one has a leak. I started looking around and trying to find where the leak was. I noticed that it was coming from around the donut where the pipe meets the manifold. The nuts were almost off the studs. Should there be lock washers here to keep the nuts from backing out?