I'm glad I could be of some assistance. Trainerdan here on this board has an AWESOME reference on CKD ( Cyclical Ketogenic Diet ) CKD is basically a ketosis based diet where you eat a low-carb, moderate-high fat, moderate-high protein diet during the week and load up on carbo-hydrates on the weekend .Here is a link to his CKD 101 thread, LOADS of information. He also has a tips and tricks books on stalls and metabolism and how they work ( I just ordered it can't wait )
As for the carb-up foods, yes you can eat fat free cookies, fat free whatever with carbs! You want low fat to minimize any gains during your carb-load ( carbs + fat = quick way to get fat ) It is also important to plan your carb-up just like you plan your weekly meals. The more body fat a person has the less often that person needs to carb-up .. as you get leaner you need to carb-up more often.
You can tell you really need a carb-up when you start to feel 'sluggish' and your get REALLY bad carb cravings, and some of your 'cheats' were probably actually helping you, but to be most effect you have to consume a fairly large amount of carbs over a period of usually 1 to 2 days ( usually the weekend for most folks )
Here is the link to the main CKD forum on this website
loads of information there.
I'm not sure of your level of exercise but cardio and general exercise is quite important on a CKD. Exercise and cardio brings you back quicker into ketosis and is necessary to rid your body of the water bloat you get from the carb-up.
It works though believe me, I was scared to carb-up, but after I did, I lost the water weight in 2 days and nearing the end of the week Im looking leaner already.
Those forums though can help you much more than I can, also the 'Quick Links' to the right of the posts the 'Which low-carb plan is right for me?' could possibly help you, it's all based on your current weight, your goal and your exercise activity level.
Let me know!