re: Canning salsa - Sorry, most likely, no.

Unless you use a recipe and method tested when making salsa, you put yourself at a risk for botulism.

CAUTION: Most salsa recipes contain a mixture of low-acid foods, such as onions and chiles. Acid, such as vinegar or lemon juice must be added to prevent the bacteria, Clostridium botulinum, from growing. This bacteria produces a deadly toxin that can cause serious damage to the central nervous system or death when eaten in even small amounts. These salsa recipes have been tested to ensure that they contain enough acid to be processed safely in a boiling water canner.

Then, there are all the recipes..
followed with :

IMPORTANT: Follow the directions carefully and exactly for each recipe. Use the amounts of each vegetable listed in the recipe. Add the amount of vinegar or lemon juice listed. You may decrease the amount of spices, if desired. Do not can salsas that do not follow these or other research tested recipes. (They may be frozen or stored in the refrigerator.) Do not thicken salsas with flour or cornstarch before canning. After you open a jar to use, you may pour off some of the liquid or thicken with cornstarch.