There are several means of preserving meat without salt: (Smoking is not included, as the first step in smoking is curing, which requires salt.)
the old worlds because they used to use it to preserve meats, in some countries salt was as valuable as gold
settlers had to quickly eat fresh kills or preserved them in winter cold rivers.
Pickling can only be used for foods that will be used pickled. Once you have pickled something, you cannot substitute it for a fresh ingredient in a recipe.
Any difference, both are sodium chloride.
Pickling lime used to be an accepted method of adding crispness to pickled cucumbers. The USDA no longer recommends use of pickling lime. Pickling lime is alkaline and must all be washed off of the cucumbers or it can result in a less acidic pickling solution. It the pickling solution is not acidic enough it can allow botulism an environment in which to grow. Botulism cases have been linked to this situation and this is the reason it is no longer recommended.
Yes
For preserving food (mostly meats).
Yes - you can use pickling salt to brine turkey. The main difference between pickling salt and other salts are grain size and iodine. Table salt has iodine, pickling salt does not. The iodine is only added to table salt to add that nutrient to our diet; it has no effect on brining turkey - it doesn't hurt but it doesn't help. Pickling salt is also very fine-grained, to speed up dissolving in water to create a brine, so it is useful for solutions needing salt. Typically it is even finer grained than table salt and much finer than rock salt or kosher salt. When you think about it, canning salt really is designed for brining processes so not only CAN you use it to brine turkey - it would probably be the PREFERRED type of salt to use to brine turkey.
Chemically they are both sodium chloride although some curing salts are a mixture of sodium nitrate and sodium chloride.
To preserve the food
dried kelp they wrapped meats like fish, muttonbird in it and smoked it over a fire
To preserve food and for flavoring. They use salt for their diets to survive also to preserve foods, and make bland foods tasty