As for the � characters you may see in some older posts, that's apparently because the character-type was changed (for the better) but some older characters didn't have a modern equivalent or something.

If you see a "�" in your signature, please edit your signature (in Settings) with a standard character and it should fix it. We'll likely have to live with those symbols in older posts that cannot be edited (if yours can be, then feel free to fix them yourself. Or if I come across any, I can do it; but it's not a high priority)...