While there is no manual, there are plenty of Youtube videos regarding the weapons. About detailed weapon information, there is symthic.com - it has all the numbers regarding the guns present in the game. I'll try to post some links when I'm home (as I'm at the university now, so I can't really browse Youtube).
Anyway, I can say a couple of words about the gadgets (although I will be speaking from multiplayer perspective).
Assault:
First aid pack - when not suppressed, it heals people in 10 HP 'bursts'. Can heal 100 HP. It is automatically 'consumed' by healed player, so he can be on the move and regenerate HP at the same time.
Medic bag - constantly heals you if you aren't suppressed and you're close enough.
Defibrillator - lets you revive friendly soldiers for few seconds after their death as long as they weren't knifed. If you just press it, you will revive someone for 20 HP. If you keep on charging it, you will eventually be able to revive someone with full health (you will hear a beep when it reaches 100 HP mark)
M26 MASS - a shotgun which can be used as an extra weapon. Can be attached to underslung rail of assault rifles to switch faster. Has buskchot (high damage, low range), dart (medium damage, a bit better range), frag (low damage, lot of suppression, don't bother) and slug (fires a single bullet, decent range, subpar damage) versions.
M320 - 40mm grenade launcher, also can be attached to assault rifles with underslung rail. Basic version fires a 40mm grenade which explodes on impact, dealing moderate damage (1 hit kill on direct hit). Then there is the Dart (fires a single shotguun-like shot with decent range), LVG - fires a grenade which detonates shortly after bouncing off something. There is also a flashbang version (which acts like LVG, but shoots flashbangs instead of normal grenades) and smoke version (creates a small smoke cloud on impact).
Engineer
MBT LAW - launcher against ground vehicles. Deals 21 damage to heavy vehicles (Tanks, IFV's, attack boats). flies in a straight line, locks on to target which is in front of it.
RPG-V2 - dumb-fire rocket launcher, kills all air vehicles except transport heli in one hit and deals decent damage to ground vehicles (18-54 vs heavy armor, depends on angle and part of the vehicle you hit), but has quite a bit of projectile drop.
SMAW - like RPG, but with less drop, longer reload and higher projectile velocity
Stinger - anti-air launcher with 350m range. Locks on to the enemy and chases him on his own once fired. Can be evaded with flares or ECM jammer.
Igla- anti-air launcher, 450m range, faster than Stinger, but you must maintain the lock-on until the missile hits.
SRAW - rocket is slow, but it goes towards the point you're aiming at. Deals moderate damage to ground units, can 1HK air units.
Javelin - ground-to-ground lock-on launcher, deals 30 damage to heavy armor on hit. Lock-on must be maintained until the missile hits.
M2 SLAM - anti-vehicle mine, can be attached to vertical surfaces, blows up when a moving vehicle gets within 3m range. 28 damage per mine.
M15 mine - anti-vehicle mine planted on the ground. 50 damage per mine.
Repair tool - allows you to slowly repair friendly vehicles... or damage enemy ones.
EOD Bot - like a repair tool, but it's remotely controlled (leaves the operator vulnerable). usually used for trolling...
AA mine - well, as the name suggests. Locks on to enemy air in a certain cone and fires once (and then blows up). Can't be used together with rocket launchers. Pretty weak.
Only one rocket launcher can be equipped at the same time.
Support
Ammo pack and ammo box - it's like with first aid pack and medic bag, but this time you can replenish ammo instead of health.
M18 Claymore - once you plant it, it shoots three wires. If anyone walks into the, the mine blows up and usually kills the enemy in front of it. Usually used to block the entrances.
MP-APS - stationary gimmick which, in theory, blocks bullets coming at it for a short while. Almost no-one uses it.
M224 mortar - can be deployed 30s after respawn. Once you plant it, hide and press "shoot" button/key to enter a console, which will allow you to aim at targets and shoot with help of a 'minimap'. Good against campers.
UCAV - remote-controlled missile with ~400m range (it can fly for 15 seconds). Can be fired 60s after respawn, has 60s cooldown period after blowing up. Kills infantry within radius of ~3 meters, deals moderate damage to vehicles. Don't bother using it vs enemies who are within 100m range. Detonates on impact, after completing one of assignments you can detonate it in mid-air.
C4 - a satchel charge you throw to get a big, nice blast. Infantry within range of blast will be blown up. Does 50 dmg per satchel vs heavy armor.
XM-25 - airburst requires aiming at a structure before you aim down sights. This will lock the XM-25 to a certain distance and make its small grenades blow up 3m after the lock distance. So, let's say, someone is behind a wall. You aim at the wall, aim down sights, shoot 3-4 projeciles over the wall, they blow up in mid-air and kill the enemy. You can use it like M320, but it's ineffective.
It also has smoke version (creates tiny smoke clouds) and dart version (makes it a subpar shotgun.
Recon
PLD -portable laser designator. Once a vehicle gets within range (300m for groound vehicles, 500m for air, I think), you will slowly start to lock on. Once the lock-on is complete, friendly units with certain launchers (SRAW, Javelin, guided missiles of some vehicles) can lock on to the enemy vehicle, fire the missile in fire-and-forget way and deal extra damage.
SOFLAM - like PLD, but you place it on the ground and it does the job on its own within a certain cone (although it CAN be used manually).
C4 and Claymore - they work the same way for Recon and Support.
Motion sensor - a ball that you can throw - it will show moving enemies close to its point of landing for about 15 seconds. You get 3 of these.
T-UGS - same function as motion sensor, but in case of T-UGS you simplly put it on the ground and it does its job until it is destroyed or you plant a new one.
Spawn beacon - you can use it as a mobile spawn point for you and your squad. Depending on map and gametype, you will either spawn on the ground or on parachute.
MAV - a remotely-controlled flying robot, which allows you to spot enemies for your teammates way easier. It can also fire a 'shot' which will blow up explosives (C4, mines, Claymores), enemy equipment (spawn beacons, T-UGS, mortars... or enemy MAV) and health/ammo bags.
I hope that helps a bit.
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