The answers are all in the Stone Edition of Chumash (Schottenstein), iirc pp. 266-267. I don't have one but there is one in shul and I looked it up again for you. I will try my best to remember the sources, but the gist I should remember.
Firstly, it states there that Joseph's job was to consolidate as much power for Pharoah as possible, i.e. that was his job and his charge (there was a quote mentioned where Joseph is saying something akin to "I would give this away to you, but I am not given permission [by Pharoah] to do that, you must buy it". He did a stellar job. He appears to have done so without forcing anyone to do anything. He originally bought all the grain required for the upcoming 7 years, and then sold it back. There's no indication of what we would call, nowadays, "scalping", meaning now that he had all the grain he would sell it at crazy prices. He seems to have just bought low (when there was a lot of supply) and sold high (when there was a lot of demand). When people couldn't afford it, he offered to sell it in exchange for other things, and that's how he got all the land.
The Stone Edition quotes Rabbi Munk as stating that there have been many famines in ancient Egypt, and generally resulting in mass death, with the land being dubbed a "land of corpses". Joseph's wisdom saved the country.
It also states that he did not enslave anyone. He deliberately didn't want to, even though they offered. IIRC the quoted sources for this are HaEmek Davar and Malbim. I can't remember the reasoning, sorry!
It also states that when it came to the population moving, for ethical reasons, he deliberately moved "communities" (the Stone Edition claims this is obvious from the pasuk itself and doesn't quote a source). Unlike the historic population relocation terror tactic used by countless conquerors (iirc started with Assyrian king Tiglaph Pilesar I?), Joseph avoided splitting up families and communities to avoid the "terror" aspect. The reason he did move everyone was because they had sold their land, and he didn't want them to retain attachment to it. It didn't explain the significance of this but I will imagine it is to prevent future rebellions. I believe this was sourced in Rashi, and many other commentaries.
Edit: I just saw this was mentioned in sabbahillel's answer by Rav Hirsch.
If anyone does have the Stone Edition, feel free to edit my post and sharpen it up.