M.T.
Hi L.,
I don't know what the p/u, p/d refers to, but it's been 10 years since I last had a baby. I never did the CIO either. From what you describe - crying at bedtime and then needing to be walked down, it sounds like he is overtired. I think it would be good to try for an earlier bedtime, preceeded by about an hour of calm time, no real stimulation. But if he's made a habit of crying at bedtime, it may not occur to him to not do this anymore (I'm not an expert here, neither of my kids ever cried at bedtime). If he's less overtired when he goes down, it may eliminate him waking and staying up during the night. I don't know what his nap schedule/habits are but look at those too. A lot of sleep issues are caused by babies/toddlers being overtired.
Good luck!