Help understanding thumbnails and crop options

A while ago–long enough ago that I’ve forgotten what I did–I made some tweaks to the thumbnail settings to get my blog, running Pinboard, looking the way I wanted. Now I’m looking over my work, and although I don’t want to change anything, I’m very unclear about just what’s going on under the hood. I have a few questions to help clarify things for myself.

1. Where are the following image sizes used in Pinboard (if anywhere)?
• slider-thumb
• blog-thumb
• teaser-thumb
• image-thumb
• post-thumbnail
2. What does the Hard Crop Post Thumbnails option do?
3. If I have used another plugin (specifically, Simple Image Sizes) to set the maximum dimensions of post thumbnails and force them to crop to that size, should it make a difference whether I check Pinboard’s Hard Crop Post Thumbnails option or not?

I recognize that some of these points might fall outside of the realm of Pinboard support–for instance, I’m sure some of those image sizes I listed above might be generated by a plugin, not Pinboard. That being said, any guidance and explanation would be much appreciated, since they’ll help me make intelligent choices in the future.

Thanks!