First Time Lordaeron Player, Questions.

Hey there, so, basically I played on another recently started server, it flopped and was pretty bad. (Shocker, right?) So, I'm going to Lordaeron now here on Warmane, simply due to buffed content and I want to re-do full progession, eg only Heroic dung gear doing Naxx, going into T8 with T7 gear, etc.

So, I'm curious with a few questions:

Population doesn't really matter, since I'll just be doing 10man runs. I heard 10 mans, are harder than 25men, is that correct?

Someone told me Naxxramas, and early tier raids have been un-buffed (removed the 300% buffs) is this true? Or is it still buffed content like at release?

Does buffs in raid, also count for Dungeons? Are they equally buffed?

That'll probably be my only questions for now, thanks in advance.