There is a secret achievement that is called "Jack the Jackal." to jack the jackal, you have to run up behind it when you are fighting it, and when you see the screen say something like "press B to enter jackal," you press B and voila! You are now in control of the dreaded jackal. Hope I helped!
On Chapter 9, after you defeat the big metal guy who has a minigun, there is a minigun on a crate available for you to use. I think it's beeter not to use it at this point. Kill everyone in the area with your Glaide or Gun, whichever you prefer. When you kill everyone in that area you can proceed to the next area. At this point, go back and get the minigun and take it with you to the next area. It is extremely useful at this point, not to mention the satisfaction. Try it, and enjoy.