a3/A takes the first three bytes and interprets them as a number (7 in this case). It then reads 7 bytes and interprets them as a space padded string (A). So, ' Bond  ' is shortened to ' Bond' only. The following A* just takes the rest as a string, removing trailing spaces. The second example is left as an exercise for the reader.

I don't understand your third question. Could you rephrase? Have you studied the examples in the paragraph that follows your citation?

$ perl -CS -E 'say "\x{3B1}\x{3C9}"' |
      perl -CS -ne 'printf "%v04X\n", $_ for unpack("C0A*", $_)'
03B1.03C9

$ perl -CS -E 'say "\x{3B1}\x{3C9}"' |
      perl -CS -ne 'printf "%v02X\n", $_ for unpack("U0A*", $_)'
CE.B1.CF.89

$ perl -CS -E 'say "\x{3B1}\x{3C9}"' |
    perl -C0 -ne 'printf "%v02X\n", $_ for unpack("C0A*", $_)'
CE.B1.CF.89

$ perl -CS -E 'say "\x{3B1}\x{3C9}"' |
    perl -C0 -ne 'printf "%v02X\n", $_ for unpack("U0A*", $_)'
C3.8E.C2.B1.C3.8F.C2.89
[download]