As neat as these ideas are,
Personally I like the idea of the icon telling us how we got it, seeing as I am an icon fanatic
but the skin one, probably wouldn't happen. That takes up a lot of memory and effort to do, not to mention just starting it all up. It's a neat idea but wouldn't happen. To tide your wonderfully imaginative brain over though, Riot did a poll to see if people would like to be able to pay a meager amount of RP to change the color of skins. It was just a poll, but it's something to hope for!
The first one's definitely a good idea.
The second one would be impossible... it works in games like MMOs because generally their are only a relatively small set of actually different character models. WoW for example has two for each race, one male and one female. LoL has ~120 different models, one for each champ, that each have their own rigging and structure. In order for your outfit idea to work, Riot would basically need to design each outfit and each accessory to work with each of those 120 champions... so basically they'd be designing 120 FULL SKINS for every outfit/accessory they try to implement... and you've seen them talk about how long making a single skin takes, I'm sure. It's just not possible for LoL, sorry :(
