I try to answer some questions though I am most certainly not a crafter:
- enhancing leather items: All enhancing of items just relies to the skill that is needed to produce them. So if an item is created using blacksmithing, you need blacksmithing to enhance the item. Leather items (= leather armor) is made by tailoring, so you just need tailoring to enhance the item
- Yes, you can add mods to an item as long as you are not trying to get more mods on it than 5 AND are not trying to add mods that are not allowend on that item AND you are not overcapping the intensity of the item OR the mod. Giving an example: You craft an exceptional leather glove (no runic crafting, plain gm made excep glove) of normal leather. You now can add up to 5 mods to that armor. Each mod will come with a certain intensity (adding + 20 lower reagent cost is more intensity than just adding + 10 lower reagent cost). The overall cap of intensity for an excep item = 550. PLZ refer to pages on uo com or uo guide to learn more about these mechanics. You will also get a list there what type of mod you can add to a certain item.
- Imbuing armor/weapons made of special material: I am not certain, but enhancing with a material or crafting with a material will result in adding mods/adding intensity. There might therefore be still room for imbuing, but I am not sure if this is correct. So you always try to imbue first, enhancing is the last step (and you will need a forged tool to do so since otherwise the item always will break).
Kind regards, Fizzle