Given the background description of some cooking related query, summarize the question into a title

Example Input: My icing is 1/4 cup butter to 1 1/2 cups of icing sugar and a couple tablespoons of milk, so I'm thinking that with so much sugar, the answer is "almost indefinitely in the fridge."So, as the title says, how long is it reasonable to keep the remnants of a batch? Although I've made small amounts (like the above recipe) on occasion, I'd like to make a big batch, seal it up, and use it as needed.(I realize that it might not work as well a month or two down the road, I'll experiment with it if I decide it's ok to use.)
Example Output: How long does butter cream icing keep?

Example Input: I had some eggs that were a couple weeks overdue and I used them in an off-the-shelf cake batter. I've had eggs that past due date before without issues but these were two weeks overdue and I thought they smelled a bit off but I couldn't be sure. Would anyone know if bad/old eggs in baking would make you sick? The eggs are cooked in the batter so I was hoping that they would still be ok.
Example Output: Bad eggs in baking?

Example Input: In the metropolitan area where I live, there is truly a great selection of dried fish in various ethnic food stores, my favorite of which is herring. However, it is always very salty and I have a somewhat high blood pressure so the doc said keep my salt intake under control as well as I don't really like salty food very much. Is the saltiness essential to the preparation of dried fish? Can the fish be as nicely dried/smoked without using so much salt? Finally, the most important question is, is there a way to desalinate the dried herrings that I otherwise like so much? E.g. I would make eggs with minced dried herring and not add any salt to the eggs, hoping that would neutralize the saltiness and the mix is still so salty I can barely eat it.
Example Output:
Desalinating dried/smoked fish