Also, are the dimensions 1000px wide by infinite height?

I think so. When you upload a photo, you will immediately be able to see it as it will appear and if you're not happy you can delete it and resubmit in a different size. Feel free to test.

Okay. Makes a difference prepping for the size constraints, imo. Nothing good or bad about it, its just a question of figuring out what looks best at those dimensions (and how best to reduce/compress the thing).

Let me check the code and I'll give you a firm answer.

Ok, yes, the height of your image is completely ignored.

If your image is up to (and including) 1,000 pixels wide, then it won't do anything.

If the image is more than 1,000 pixels wide, it will scale it down to 1000 pixels wide, adjusting the height to scale properly.