My fav is pork drippings. Cold onto dark ryebread with lots of salt. Very healthy for the mind, not so for the body. And if there's any crackling left sit it on top...oh yes :)
Don't like chicken or lamb fat.
Beef dripping and pork drippings, and bacon fat are great for roast root veg, even cabbage. Certainly for onions and mirepoix. So much flavour. Try roasting tomatoes in any of them - great flavour.
If you are making chunky lardons, the bacon fat will help get them going. They are not the same as bacon where you start that in a dry cold pan, they need a bit of fat to get them cooked properly and then it draws out their fat. So now you have more fat to use
If you are making meatbals with very lean meat, incorporate fat of choice to keep them juicy.
Have no idea about duck or goose fat, don't cook either of them, but I hear duck is particularly good for roast potatoes.
Try looking into recipes for potted shrimp - you may be able to substitute butter with some of your stored fats, or liver pates and the like.
Re: labelling items - I find masking tape useful . Not sure what it is called there, but you know when you are painting a wall and trying to separate the areas of different colours, its that tape. Pretty much paper-based tape. Can write on it, tape it onto container/ zip-lock bag etc, then once you've used the contents, it just strips off easily.