Sorry to all,probs with the keyboard which is no excuse for not looking at what I have written,
17 Across, Original message(4)???D
2 Down, Port certainly German wine(5) R????
12 Down, Foaming algae get spilt,for sloppy(4) F?O? S?I?T?E
14 Down, Forced good king,having lost top 17?(9) G???E?E?S
16 Down,Batting position,for example(8) ?N?????E
The reason I suggested card is that someone who is a bit of a character is said to be a card or an original, and birthday cards, xmas cards etc. are messages.