1. Are you talking about editing replays? You can already do that.
2. This is what item forgers are for
3. We have plenty, plus we have joint/body textures.
4. You can make your own mods.
5. What do you mean by auto download?
Also support is for technicality issues with the game itself and this thread would probably best fit in the suggestions board, if you can make a couple better suggestions.