App Deployment

I am really new to Intune and how it works, and I have been working with it the last month and now I feel like I have a pretty good understanding of how it works from a setup standpoint. As I start to look at app deployments it gets me thinking about best practices. I have tried to find something that would help me out with this but I cannot so I figured I would try here.

1. First question when it comes to groups for app deployments would you create a group Per App deployments, or would you create a group for more general apps and then more specific groups for specific apps?
2. Second question, Lets just say I create a group for multiple app deployments and I want to uninstall an app in that group. I do understand that I can go into the app deployment and under the uninstall section point to another group for it to be uninstalled. I have done this but for the app to be uninstalled I had to remove the device from the install group and then move it to uninstall group and it would install. Is that how it works?
3. So building on the 2 other questions Is this the correct way to remove apps? My issue or thought is that if I have to do this.. then I would have to move the device back into the original group to get back the app if want. 
4. Last one on this thread is it best practice to point deployments to Device Groups or User Groups? I would assume Device Groups because then the system would not try to install for every person if multiple individuals log on to the device. 
   
   Thank you for everyone's input