What’s the benefit of a steel-toe boot?

I am shopping for new boots, but I don’t really know how they should fit. They always feel fine in the store, but when I start using them, my feet kill me! What should I look for to get the best fit?

How do I know if my boots are resole-able? And is it worth it?

There is a huge size difference in my feet and I’m tired of having one great fitting boot and one that’s way too big! Are there are boots out there that I can get in different sizes for each of my feet?