Widgets are "live" applications which can be used directly on the screen you are looking at. They are capable of showing real-time content.
So, for example, I have installed a version of the launcher called "Launcher Pro". This replaces the stock TwLauncher which comes defaulted on the SGS. Once installed, for about £2, it is then possible to put Facebook, Gmail, Twitter, Calendar widgets directly onto the screen so the content can be read instantly, rather than having to first choose a shortcut which loads an application and then presents a Twitter feed, for example (iPhone style).
I wholeheartedly recommend the "Launcher Pro" instead of the stock Launcher which comes with the SGS. It's fantastically customisable and makes the whole experience of using the phone much more enjoyable. There ARE others, but this is very popular.
Try downloading Launcher Pro and Homesmack (an app which allows you to switch between the two different launchers)
1. Presumably I would have to move all the apps 'manually' as it were, but presumably I would have to make some 'holes' for them first?
2. As I understand it, I can then move them around to any order I wish on each individual page.
3. You mentioned Widgets... are these sort of 'short cuts' to actual applications, or have I got that wrong?
Re: points 1.+ 2.
Yes, what I do is on the last app page click menu > edit. A spare page is automatically created. I use this new page to put all the apps I don't use, from each of the previous app pages. This creates the "holes" so you can now move the apps around.
When finished click menu > save.
You can move the App pages around by using the "Pinch to zoom" motion. All the App pages are displayed at the same time! Just drag each page to it's desired position.
Re: point 3.
Widgets are mini versions of a running App. A Clock on the Home screen is a Widget! These are accessed by a Long press on one of the Home screens, This brings up a Menu of available Widgets.
Widgets and App pages. Use pinch to zoom to display all the app pages.