You would need to look at the documentation for each of the encryption types in the PHP site.
RIJNDAEL is a little different than the others though though in that there is not a static string length. encrypting the same value different times will give a different encryption string and each will have a different length, so theres not really a way to know what the string length will be, and I haven't found any mention of max length.
theres not an easy way to encrypt existing data without reentering it.