to hash or one-way-encrypt data with other algorithms than md5 either see crypt() or use sha1(). for real en/decryption check gnupg implementation in php you may also check http://pear.php.net for other usefull things here.
i don't know. I can't search more in the www than you can (google would guide you to usercomments like the following). Btw are you looking for something specific? As you mentioned some (hasing) algorithms above, but not sha256 but even the much weaker md4...