A couple things about Flickr - and perhaps it is only because I haven't taken enough time to really check out the site as much as I want to -
I saw that they suggest you resize your photos before you upload them, but I didn't see the place where you could do that. I am also wondering if there is a way to choose the size of the displayed photo. I will keep looking as I work through Things 5 & 6. Maybe the answers are already out there in those things - but I tend to do things in order and haven't looked ahead.