@Kyoji:
Well, since they left for a world government non-member country, how did that people suffered with Celestial Dragon's oppression? Don't make sense, since the CD are related with the WG, they shouldn't even bother themselves to go to a non-member place.
Also, how did they realized they were former-CD if they aren't even allowed to look them in the face? Did the CD somehow spread the news to put the population against the family? It could make sense since the CD themselves left Dofla's family in that place and provided what they'd need.
Any explanations?
I think CDs go wherever they want. The threat of an admiral is same for everyone, whether they are part of WG or not. And they always travel with their private guards who aren't much to the likes of seasoned pirates, but are probably more than enough to take care of normal people.
As for your second question, I suspect Dofla carelessly revealed their identity in the town, while talking about slaves and shit.