Hello there
1) Yes, we're still thinking whether to add purchasable Avatars (for Gold, of course) or even something more particular: the ability to "sync" your community Avatar with the one in the game, so whenever you change your profile picture here, it'll also change in the game. We're evaluating pros and cons of this though, as we'd need to have some kind of "control" over the images uploaded by users.
2) It's something we'd TRULY LOVE doing, but so far we're having some animation barriers which are blocking us, as we're not yet talented enough with that, but we'll work on in, maybe with something simple, to begin with
3) We also considered this as a "plugin" which could even sync with our community chat, too. We'll see what we can do
4) Trading could be fun for sure, but we're afraid it could be exploited by users making alternate accounts to take advantage of this, which we think would be unfair towards others. We'll think about it though.
5) You have my word, this game was made to be played and enjoyed by everyone, without any pay-to-win features, as the fact we don't have any In-App Purchases is one of the main fundamentals of our game, and as you pointed out, it keeps the "nostalgic feeling" we aim at