Solution:

It's shown in the red circle below.

Solution:

Three possible ways are shown in the image below.

Solution:

It can be solved as below.

Solution:

Microsoft (Mic + Crow + Softy)

Solution:

It can be solve as shown below.

Solution:

The Lady sitting in the chair has the detector attached to the back of her blouse.

Solution:

Can be done smartly as shown below.

Solution:

I have three theories based on which it can be either Murder, Suicide, or Accident.

Case1 : Its a Murder
Reason1: If it's suicide then a person must have waited for the Cigarette to end.
Reason2: Blood is spattered on the right side and the pistol is also on the right side. which seems pistol is planted at the end.

Case2 : Its a Suicide
Reason1. The lamp was switched off and glasses were removed which indicates she done writing(probably suicide note). The murderer does not care about switching off glasses or removing glasses.
Reason2: The blood was just on the wall at the height of a person. If it's a murder the blood must have been scattering around.
Reason3: Burning cigarette and alcohol indicated depression level which often is the reason for suicide.

Case3 : Its a Accident
It's must be an accident. The girl was writing using the pen and suddenly she heard a sound. She must have a gun for safety which she takes out of the security. As a preventive measure, she switched off the light so that she can't be seen in the dark. Also removed the glasses as they are of no use in the dark. After a while, she realized that it's just a sound. So to calm her down she drinks and also lights a cigarette. suddenly she slipped and try to hold stool but failed and forced her head into the wall and died.

Solution:

Notebook

Solution:

30

Explanation:
It's very difficult to count an actual number of balls but it can be counted mathematically as illustrated below.

Balls in lowest level most level, say level 1 : 4 * 4 = 16
Level2 => 3 * 3 = 9
Level3 => 2 * 2 = 4
Leve4 => 1

Summing up 16+9+4+1 = 30.