It's also important to make sure that you're FIFOing properly in and out of the backroom as well. In produce, you should be pulling items with the oldest Bcode date on them first, and in meat, the items that have the closest expiration date first. Keeping items with the same DPCI in the same location as much as possible, and organizing them by date will be a huge help with this.
Whoever handles your food truck backstock should be Bcoding each box with the UPC label and date. Since the majority of produce sells by freshness and doesn't have a printed expiration date on it, the date of receipt kind of serves as an "expiration date" of sorts for the market team, so that we know how long it's been in our store, and if we need to put it on TPC to sell through short dated product, or excess inventory. We also made labels for produce that sells by the each (lemons, apples, oranges, etc) and stuck them in a couple of those 12-slot softlines label holders and put one in the ambient room, and one in the produce cooler just in case the Bcode labels fall off (pretty common for bags of onions, potatoes, etc).
And yes, you should always pull the entire casepack, and backstock partial casepacks. Make sure you type in what you're actually taking out of the location though, and not what the PDA is asking you to, or else your counts are going to get messed up.