You seem to have the bases covered so to speak.Give it a shot for a while, and if you get stale after some weeks, make some change. Overall, I think it's a good starting plan for health and overall general fitness.
I agree with TimD. It's better to spend your time following a good routine than procrastinating while planning a great one. Once you get stale on a given routine, you can make changes.
Will the deadlifts do enough work for my lower back, or should I do lower back instead of abs work on one of the days?
As several posters noted earlier, your routine has ample work for the lower back. The standard deadlifts work the lower back isometrically, while the stiff legged deadlifts work the lower back through a range of motion. My mistake - I focused on doing isolation lower back exercises to balance the ab work, forgetting that the compound deadlift movements are more effective