I've searched for this answer, but either my search-foo is weak, this question hasn't been asked, or the answers are so blindingly obvious no one has had to ask them before! So, here goes...
What do the factory preset names tell me? I think the "FX" prefix tells me the preset contains only effects... no amp/cab. Is this correct? If so, then I assume the "DIR" prefix tells me there is an amp/cab setting, but what does "DIR" stand for? "4CM" probably stands for 4-cable management, correct? BAS is probably for Bass players, ACO is for acoustic, and KEY is for keyboards. How am I doing? I don't have a bass or keyboard, so I would be safe deleting those to free up space for new presets, either my own or those I buy/download, right?
Letters at the end of the preset name are usually the initials (or other identifier) of people who created the preset, like JNC is John Cordy. Do I have that right? Any enlightenment would be greatly appreciated, and thanks for your patience with a newbie!