well there aren't boy and girl sizes there just sizes
Statistically, for length, boys feet are wider than girls feet. In other words if your feet are 10 inches long and you a boy, they may be 4 inches wide and if your a girl, they're closer to 3 inches wide. The same differences are true for glove and ring sizes.
girls
It depends on what you are asking. In the UK shoe sizes go up to 13 (childrens' sizes) and then start again at 1 upwards (adult sizes). However as far as the government is concerned childrens' shoes stop at adult size 5 for a girl and size 6 for a boy when they start to levy VAT
Not much, sometimes woman's skinny jeans may have no pockets and might be a tad stretchier.
A Boys body is different that a girl's body, Mosti likely a girl's 7 will fit a boy's 5.
No, they are larger by 2 sizes. So a boy's size 6 is the same size as a girl's 8.
The range sizes available for the keyword "shoes" can vary from small sizes like children's shoes to larger sizes like men's or women's shoes.
Shoes
I don't know about children's shoe sizes, but for adults, it is two sizes different. For example, if a woman wears a size 7 shoe, then she would wear a size 5 in men's shoes.
Yes by 2 sizes
These are the sizes ive found that they have sold in. They sell in sizes 6 and 6.5. Yes they do sell shoes in the half sizes as you asked. They also make the sizes all the way up to a 11 in womens shoes and a size 12 in mens.
A,B,C,D,E and so on.
yes it's fine as long as there not girl shoes lolalot of men seem to have alot of shoes its absolutely fine:)hope i helped.