Yes, Kermas forces were decisevely destroyed in the year 2 of Thutmosis I reign. There were rebellions until the reign of Thutmosis III though and only at that time the rule over Nubia was consolidated.
If your sources are from the 1500-1000 BC that might be true, but i havent read anything yet about the Kerma-Elite beeing Egyptianized. For example the burials were totaly different from Egyptian ones, including cow- and human scarifices. The shape of the grave is also different: While in Egypt we have our pyramids, we have in Kerma big tumuli.Of the research I have seen, Nubian clothing in the higher ranks of society was pretty egyptianized...with its own distinct flavors however.
A Nubiologist (Dr. Michael Zach) i once asked about how trustworthy Egyptian depictions of Nubians are told me that: Egyptian paintings make use of stereotypes.I cant imagine its a stylistic convention in Egyptian art because assyrian art also shows the feather kilt setup as well.