ek pretty much summed it up... but i will say it again in a lil more detail...
1. As you reach higher lvls the value of leather will increase (light, medium, thick, rugged) as well as other hides/scales and other stuff. A LW is pretty profitable at low lvl but the real cash comes in when u hit 60, some instances have monsters which need 305 or 315 skinning which can be obtained by either the enchantment (see 3.) or finkles skinning knife (see 2.) some of these monsters are the only monsters in the game that drop certain scales, so are rare and therefore, proffitable. So yes... it is worth it compared to the other proffesions.
2. The skinning knife is just an item u need in ur bag not to equipped, so without that you couldnt skin, however there is Finkles Skinner
http://thottbot.com/?i=13374
which increases skinning by 10, so along with the enchantment (see 3.) then u can skin anything in the game (i think)
3. The recipe for +5 skinning to gloves is dropped by the witherbark shadow hunters, beserkers and headhunters in arathi highlands, each one having about a 1.1-1.3% chance of dropping it, so there may not be loads of ppl who have it, so it may be expensive depending on server of course. The mats are x1 vision dust and x3 red whelp scales, which u can get off red whelps in wetlands (they are lvl 23-25 so u can kill them easily) find an enchanter who has recipe, provide most mats (or buy one vision dust to provide all mats) and hope for a small fee or free of charge =D
Hope this has helped...