Wow was 5.10 the only NW? If so that is great.
Regarding weaning the dummy, I'm no expert as we have never used a dummy. Could you perhaps start a new thread in props for some more expert eyes? I say a new thread as more people will look at that and give you advice than they will a new question in this thread which is quite long now.
I do think the dummy dropping out is becoming an issue and causing him to wake everytime he comes into lighter sleep/it falls out.