These days any hacker can break short passwords - especially if they really are words (or names). And no, you don't get a newsletter - but it does tell you when someone replied to your post.
To change your profile photo, click on your avatar at the top of the page and choose Edit profile - though I'm guessing you already did.
If you use Sync or these forums, you have to provide some information to register - your email address at minimum in order to allow you to reset your password should you forget it. No, Opera does not record your financial information or comparable private data - that would violate a number of laws.
@leocg My guess at this point is that when the changed the forums over it reduced all the post-counts for users to zero. Just a guess but it seems to fit the available facts.
If you remember your username or the email address associated to your account, you can try retrieving your password. If you don't, then there is nothing that can be done.