Yes, Chest and Back is a pretty tough intro to the rotation! I personally was intimidated by it on previewing, so I left P90X on my shelf for weeks before I decided to try it, then I kind of started "in the middle" with Shoulders and Arms (much less scary!).
I had the same experience others had with Ab Ripper X: I felt the first three exercises or so more in my hip flexors than my abs at first. Just keep doing it, and soon you'll be able to engage the abs more. Strange thing, even though "Ab Ripper" often ended up being "Ab Skipper" for me, I had great results in the ab area (probably from Core Synergistics and the Plyo workout as well).