As far as I know, there are no prerequisites for pro jobs (I saw them from the lowest reputation levels). The difference in comparison to normal jobs is that you cannot try the mission again if you fail. You get one try and that's it.
Another thing that makes pro jobs special is that there are no pro jobs on normal difficulty. They are always on hard, very hard or overkill.
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.
Best Answer
All of the AI will carry the same weapon based on the character, not what the host has equipped; Dallas and Hoxton appear to be carrying an AK-47 with a folding stock, Wolf seems to carry a Compact-5 with an adjustable stock and the "Polizei tactical" foregrip, and Chains appears to carry a CAR-4 with holographic sight. They will always carry and use these weapons with these mods, regardless of what the host has equipped.
I determined which weapon each person had based on the viewmodel I saw and the rate of fire (to identify the rifle Hoxton and Dallas use as an AK-47).
The fact that they seemed to carry the same weapons as you was simply a coincidence.