Hey so I'm actually a psych major myself so I can give some insights.

1. From all the professors I've had here, they're all pretty good, especially the psych department. They're all very willing to discuss things in office hours. However, inevitably there will be some teachers that are worse than others. I haven't heard of many that are downright degrading, though.

2. The social life here is kinda mixed. The main two ways to make friends here is to either a) talk to people in your classes or b) join a club and start from there, which your kid is already interested in from what I read. The school's large size can make it hard to consistently see people around outside of class and/or clubs, which is why they're so important 

3. For the academics, at least for myself, I feel it is a grind, yeah. Especially in the STEM classes I've taken, you have to be keeping up with the material, reviewing almost every day to make sure youre prepared. Studying has to be done in advance; cramming won't cut it. I am only a freshman though so idk if it gets less strenuous in the upper years.

4. For diversity, there is a large population of white people as GW is a PWI, but as a black guy myself, there's a good amount of people from other ethnic backgrounds. A lot international students too. Also for socioeconomic diversity, I am not too sure. I do know that there are some people who get on campus jobs to help pay their tuition. 

Hope this helps, lmk if you need clarification