I think it is possible he will relax and get into his own routine, yes.
As far as getting along with a new friend - again, it's up to the ducks. Take the introductions very very slowly. Don't just put them together. Seriously, it seems like they need to see each other for quite a while at...
It's always up to the individual ducks - watch for any interest the duckling may begin to show in mating with chickens - that can be fatal to the chickens. Of course, he may be a she, in which case that's not a concern.
As long as the duck is healthy, that's good - so also watch that the...