Good idea on holding of on the xanax cocktail. With the norco and oc it seems you know your limits and your questions have been answered so I'm not going to comment on the amount you should take. Personally taking them on an empty stomach does work better for me however I can't say there's a "right" time when you can eat. Like I said originally just wait until the effects peak and then eat. I have noticed on rare occasions I'll get a little boost after I eat but I really don't think thats common.
I do promote cwe but that is one point I'll agree with you on, you aren't ingesting a lethal dose of acetaminophen nor will your whole body turn yellow. Just keep it under 4000mg in a day, and start cwe's if it's going to be a regular thing.