As an Xbox 360 player I have had no trouble putting children's rooms in the original homes and have always moved the family to one of the Hearthfire homes first. Both my characters have adopted most orphans at one point, they all seemed the same. What problems you have because of incompatible mods and patches is not a problem with the DLC. You will just have to find out which mods are causing the problems and get rid of them.
Yes sophie the flower seller from WIndhelm can glitch, but I do not see how being over encumbered is related to moving her to a local house first, I have adopted her twice without problems, always moved her to a hew house, as a PC player you should be able to fix that problem, if it occurs.