Need Technical Advice

I'm working on a webpage which will have a lot of pictures. It'll be several pages when it's done. Presumably, all the files for all the pictures load and then the server sorts out which pictures go on which page?

At the moment I have everything in one folder. It's an on-line thing, and it says I can make a new folder. Before I click on that, I'd like to know what difference it will make.

Sould I make a new folder for each html page, and put the pictures that are to go on that page in that folder? Will it be quicker loading then?

The pictures are gifs (it didn't like jpgs or bmps), and only about 10KB each. How many can I put on a page and still have it open reasonably fast?

I have some pictures that go on all the pages (gifs at the top) - where do I put them?