From experience in CG (360), I found that heat seeker on often provided some strange wtf animations from defenders where they would open their arms to wrap tackle somebody, and then they would just let them go by, so for me personally, this did NOT work out well. I am not positive in NG, but I personally didn't find much use out of the heat seeker when I did try it out, so for me, it's out. Feel free to try it out and let me know if it works/doesn't work/pulls out strange animations.
Auto-strafe is off because I don't like the cpu doing that for me and feel that they do it too long putting me out of position, so this is something I want to be in control of and enjoy being in control of. Once again, you can probably get by with it on. I don't believe it will make the sliders play much differently, if at all, but I feel it takes away some control to the user, so i don't like it. Totally a personal preference on that one.
Try em both out if you've been using them before, and let me know how it plays out.