Are the bonuses from Silent Killer cumulative

So far, from what I could read online (in this guide and on the wikia, among other sources):

Briefing screen

Pay grade

The pay grade for a mission indicates how much cash players can expect to get out of a mission -- source.

Also this thread suggests it can go up to 10 stars.

Day rate

The dayly income rate is a cash reward with a multiplier for the day a heist takes (e.g. 1x in The Bank Heists and 3x in the Rats Heist) -- source.

Contract pay

The contract payment is a flat amount of cash reward based on the number of white stars (pay grade) -- source.

Payday

The overall payday is the sum of the other two cash rewards (pay grade and contract pay) and will be shown on the map if you select a heist -- source.

Yellow bonuses
These bonuses come directly from the difficulty (or "risk") of the mission, pictured by the yellow skulls on this very same screen. Normal = no skull -- overkill = 3 skulls.

Debriefing screen

Instant cash and bag loot items
The instant cash it the one you loot and put in your pockets directly during the game (jewels, cash bundles, ...) The bags are those heavy packs of money, jewels or even drug you'll have to carry in order to achieve a mission.

Balance
This section contains the sum of all the amounts contained in the Income section ($332,400 in the example given in the question) distributed between two type of accounts: the offshore account and the spending cash.

Offshore account

The offshore account consist of most of the money players steal during the course of their heisting career. The player has no way of interacting with their offshore account and is only used to show off how much the player has stolen -- source.

Since August 30 2013, you can use your offshore account to directly buy specific missions from Crime.net.

Spending cash
The cash you get, finally. In the given example, it's 10% of the total amount, but so far I couldn't find any precise calculation to know if that percentage can vary or not.

This is the offshore account money and 10% of that becomes you spendable cash. -- source.

The following abilities will affect all weapons:

• Leadership (when Aced)
• Hard Boiled (when Aced)
• Overkill (when Aced)

The Mag Plus skill in tier 6 of the Technician tree increases magazine size for all weapons that do not have a fixed magazine size. This basically means "all weapons" excluding the Bronco (it's a revolver...) and the Mosconi 12G (it's a double barrel shotgun...).

In addition to the above, each class of weapons gets additional bonuses as follows;

Pistols

Pistols are affected by the abilities Equilibrium, Gunslinger, Leadership and (excluding the STRYK 18c) Sharpshooter. The pistols in game are as follows;

• Chimano 88
• Crosskill
• Bronco .44
• Bernetti 9
• STRYK 18c
• Deagle

All pistols are secondary weapons. Pistols fitted with silencers (the Bronco .44 cannot be fitted with a silencer) also pick up bonuses from Silent Killer and The Professional.

Shotguns

Shotguns are affected by the abilities Shot Impact, Shotgun CQB, Hard Boiled, Overkill and Sharpshooter. The shotguns in game are as follows;

• Reinfeld 880
• IZHMA 12G
• Mosconi 12G
• Locomotive 12G

All shotguns except the Locomotive 12G are primary weapons. It is possible to silence all of the shotguns apart from the Mosconi 12G, and doing so will pick up bonuses from Silent Killer and The Professional.

Submachine Guns

Submachine guns get bonuses from SMG Specialist, which can be aced to provide further bonuses. The submachine guns in game are as follows;

• Mark 10
• Compact-5
• Para
• CMP
• Krinkov
• Kobus 90

Submachine guns are secondary weapons. They can also be fitted with silencers allowing them to pick up bonuses from Silent Killer and The Professional.

Assault Rifles

Assault rifles are affected by the abilities Kilmer, Rifleman and Sharpshooter when aced. The M308 rifle is considered a single shot assault rifle due to its semi automatic nature. This means the M308 rifle picks up bonuses from Sharpshooter to reduce spread, in addition to the aced bonus.

The assault rifles in game are as follows;

• AMCAR
• AK
• CAR-4
• UAR
• JP36
• AK .762
• M308
• AK5
• AMR-16

Assault rifles are primary weapons and they can be fitted with silencers, allowing them to pick up bonuses from Silent Killer and The Professional.