Good questions Skinyea.
I just started a new thread aimed at collecting storage methods and recipes that folks are currently using. I'd invite you to post up your freezing and dehydrating methods there.
It's that time of year in Texas to harvest and store the spring crops. From now until August, we will be harvesting and storing our food for the year. I'm hopeful we have enough interest in this thread to get some new ideas, recipes, and techniques for storing our garden produce and prolonging...
www.gardening-forums.com
My answers to your questions:
1) both are valuable tools depending on the type of veggies
2) no, vinegar isn't always required but is in certain situations
3) my families going back generations on all sides have had "canners". We can now based on that history...but unfortunately I didn't learn near enough of what they tried to teach me. Safe? Not one, none, incidents of food problems going back more than a century.
4) all kinds of ingredients can be used...according to your tastes. Generally, recipes are suggestions that can be tailored to your tastes. How ever . the specific steps in a process whether water bath or pressure canning or whatever that are recommended in credible books should be followed without exception.