How was Gondor founded?

[eothain of fenland]

I know that during the Numenorean era, there were many settlements all throughout Middle Earth, and that some were in Gondor. Once Sauron was captured and brought to Numenor, he corrupted them, and their home sank and almost everyone died yadda yadda yadda. Elendil and his son Isildur (?) have foreseen this, and they were prepared to leave.

My question: did the natives of Gondor (probably of the same stock as the Dunlendings) fight the more advanced Numenoreans upon arrival? Did the followers of Elendil just settle in the old Numenorean settlements? If so, then was there war between the first Numenorean settlers of Gondor and the natives?

Since the Gondorians are considered 'the good guys', Tolkien, of course, isn't going to portray them as conquering the lands of the less-educated natives. But, how else could they have settled there? I doubt they would just welcome in these foreigners.