Yes, it's a good price. I paid £18 for mine, which was good. Mine does have a 'V' in the middle though which, as others have said, is much more useful for clearing cables, down-pipes etc.
Ah that makes sense. Pretty niche... Hard to guage if £14 is a deal or not.
Yes it stands your ladder off the wall, useful if you need to clean or repair gutters that stick out past the house to stop you leaning out
No good if there is a drain or soil pipe in the way. Better to have one with a gap in the middle.
I think you attach it to the top of a ladder and it allows you to rest the ladder out from the wall. Useful if you need to drill a hole with a long bit for example.