Power Management on LMDE 7

I am running LMDE 7 on a Dell 7200 tablet with some problem on power management.

I installed the 'PowerMan' applet for power management automation, but there are some problem with it.

1. I setup to display the battery level with time reminding, that worked fine at first, but the timer disappeared after some use, I checked the setting of the applet and nothing has changed.

2. Screen saver worked half of the time. I set to turn off screen after 5min of inactivity, but that not always work. Some times the time clock screen saver will show, but the screen did not blackout after that, it should blackout few seconds after that/

3. There are 3 levels of power profile Power save, Balanced and Performance that can be set according to battery or AC in use. I set Balanced when charging and Power save when using battery, that worked but not as expected. When I remove the charger the system still stay as Balanced, but suddenly after some use it will pop up with profile changes. The same problem when I plug back the charger. I wonder if there's any other similar apps I can use to fix the problem.

This is about using LMDE 7 on a Dell 7200 tablet, I can't test it on PC without the volume control hotkeys.

When I press the physical volume key on the tablet it will auto repeat few seconds, so that it is hard to control proper volume, it always overshoots, any idea how to fix that ? it doesn't look like a h/w button fault to me, or it will random auto jumps.

What Desktop Environment (DE) are you using? Could you please provide the community with the requsite log files. Which are stored in /var/log/ file system.