jyxavier, first of welcome to the forum, and I hope you enjoy your stay here.
Don is probably best to answer your questions (so please feel free to remove my post if it is incorrect), but I will take a quick shot at it.
Using an alphanumeric password, should always be best practice really, and this is something that the forum can require as a minimum and is set that way accordingly. Its not a bad habit to get into.
Sending your password in the email is probably a function of the forum tool on first setup. I see where you are coming from about the security aspect, but at the same time it is just a password for a forum, not bank account credentials, and now you are signed up you could change your password online (I assume that doesnt generate another mail).
As for the forums not using HTTPS, again this is a forum, I dont think I can think of any that use HTTPS for forum authentication. It costs more money to have a secure protocol in use, and adds a small performance overhead and it just wouldnt be justified.
Again enjoy your visit, dont be afraid of the search button, I am sure many questions have been asked before, but dont be afraid to ask. We are all here to help, just try and keep the questions ethical.

This post is secure

I just hope the lock isnt shimable.