Do I set up a discrete graphics card in the laptop for maximum performance?

So there is a laptop HP Pavilion 15-p055sr G7W94EA

System type:
Intel(R) Core(TM) i5-4210U CPU © 1.70 GHz 2.40 GHz
64-bit operating system, x64 processor
Memory frequency 1600 MHz
Memory type DDR3L SDRAM
Random access memory (RAM) 4 GB
Integrated graphics+GeForce 840M 2 GB
Hard disk 500 GB Seagate ST500LT012 Laptop Thin
The rotational speed 5400 rpm
Use for programming in C/C++/java in eclipse and idea and surfing the Internet using chrome.

As I have little RAM, and integrated graphics card uses for itself, the RAM of the laptop (which is only 4GB), I decided to only use the discrete card with its own memory, by configuring the program "nvidia control panel".

Actually 4 questions.

1. If I'm right that involves only the discrete card only by selecting it through the "nvidia control panel" (see figure 1 ) or embedded videos should be off on the other?

2. Do I set up a discrete graphics card in the laptop for maximum performance (see figure 1)?

Figure 1.


3. Why not in all programs it is possible to use a discrete graphics card, especially windows applications and the various video players (see gif)?

GIF



4. Why some programs - nvidia uses all global settings except for "power management" and it always puts Adaptive and not maximum performance as a global parameter (see figure 2)? Can adaptive mode better mode max. performance?

Figure 2.



P. S. whether it is Possible for the laptop to completely shut down integrated graphics?