1: No.
2: As a short answer:
The 65th character ("=" sign) is used only as a complement in the final process of encoding a message.
You will not have a '=' sign if your string has a multiple of 3 characters number, because Base64
encoding takes each three bytes (8 bits) and represents them as four printable characters in the ASCII standard.
Details:
(a) If you want to encode
ABCDEFG <=> [ABC
] [DEF
] [G
Base64
will deal with the first block (producing 4 characters) and the second (as they are complete). But for the third it will add a double ==
in the output in order to complete the 4 needed characters. Thus, the result will be QUJD REVG Rw== (without spaces).
(b) If you want to encode
ABCDEFGH <=> [ABC
] [DEF
] [GH
similarly, it will add just a single =
in the end of the output to get 4 characters.
The result will be QUJD REVG R0g= (without spaces).