The
Mangled Bundle is a refining recipe you get at level 4 (not 3 for some reason) and is the basic processing recipe for tier 1 leather.
The Primary Component listing is a "ItemX" OR "ItemY" OR "ItemZ" kind of list - so in your example above, the recipe asks for a mangled bundle OR any one of the others.
The Drifter's, Brigand's, Sentry's and Mystic's Bundles are bundles that have been enhanced, at creation, with one of the special dusts crafters can use - if you look at the mangled leather bundle recipe, you should see a line that will let you add a... gah, I forget the word, might be "catalyst" - that would be the dust. Enhanced bundles are made just like normal mangled bundles except that at a given stage in the process the dust you added to the table is incorporated into the thing you're making.
As for your leatherworking skill, that sounds odd. One thing to check would be to make sure that the skill isn't locked (open the char sheet, crafting section, skills tab at the bottom), or indeed maxed out. If the latter, you're obviously doing something right. :-) If it's not locked of maxed chances are you just don't have any available points because they're already allocated across all three skills in that group - tailoring, leatherworking, outfitting. The beauty of the system is that we don't get enough points to max out all 3 skills in a group, so you'll have to reduce one of the other two if you want to increase leatherworking. If you intend to specialise as an LW rather than a tailor, you could set tailoring to go down, or just lock it so that when you level it doesn't go up and the points can go into LW.
After all that, if it's none of the above, you need to make sure you're getting WOs from the finishing taskmaster (refining ones won't raise leatherworking) and, as you've already noted, make sure they're leatherworking recipes. You mentioned that though, so I suspect the issue may be that you simply don't have any points available for it right now.
Keep asking questions. Helping out makes me feel useful!
