They are based on the Worth Valley Railway near Keighley in West Yorkshire (http://www.kwvr.co.uk/) and are often in use for the public to travel in during special events. They are owned by the Vintage Carriages Trust (http://www.vintagecarriagestrust.org/) and the Lancashire and Yorkshire Railway Trust (http://www.lyrtrust.org.uk/) - one of theirs is the unique Blackpool Club Carriage of 1912, which was partly refurnished on set to be Winston Churchill's travelling office.

why?

ok i think i know it know, I watched the second episode. Is it for fighting purpose and to show that they are in the "gang"?

Identification is two fold, one is to be a member of, while at the same time be anonymous (which foils prosecution). Think of the term "hoods," a device which was so commonly worn by criminals to avoid identification that it became synonymous with "criminal." In the modern era, the use of large down coats or parka's on inner-city gang members both creates anonimity and misidentification, and allows them to carry weapons or contraband. In the case of The Wire, one gang member was chastised for having a pronounced ponytail, because it made him stand out during survellance, where as the other dozen gang members present all belended together.

Not sure, but I thought it was the standard military hair cut (short back and sides) and the older ones had it because they had just got back from the war and the younger ones had it because the elders had it. Also I think it was quite a common haircut.

Standard military haircut prior to WWI wasn't that short at all. This kind of haircut was "popular" or, indeed, mandatory in the trenches during the war as it would minimize accidence and/or make easier to spot and exterminate lice, which could transmit the typhoid.

This was a common style with almost all working class and poor in both the U.K. and U.S. It was also expensive to get a haircut on a regular basis and many men either did their own cutting or had it done shorter so the cut lasted longer. During WW1 it was determined that longer hair was easier to grab during hand to hand combat. These were all factors that combined to make this a logical style for the period. It has literally nothing to do with gang affiliation.

Reasons are unknown. Scripts were written but not titled.