This will depend on what Country you are in and the side of the road you drive on there.
1st: "U" turns a dangerous and have to be done carefully and in a lawfull manner.
In North America the Car making the U turn is almost certainly At Fault. A U turn to the right is not Leagle to do.
In England or Austrailia (for example only) we need to look at was the U turn Leagle in that location, Was it done from the correct lane, was it done having signaled properly and so on.
If the U turn was 100% leagle and done correctly the Car striking from behind is at fault.
If the turning vehicle was struck by a vehicle entering the roadway it would be the the fault of the vehicle entering the roadway.HOWEVER, if the entering vehicle was struck by the turning vehicle, it is the fault of the turning driver.
right turning car
If you are in a turning lane, and the other vehicle turns into you while they are in a straight lane, then they should be at fault. If the accident ends up in court take photos of the intersection to help plead your case.
if you where paying attention when you turned then it the other pesons falt but if you weren't then is your fault.
driver 2 Probably Driver 1, the driver making a right turn is usually considered to have the right of way.
B is at fault. Drivers making a turn, must yield to oncoming traffic. B is at fault for making a left turn without yielding. There is no general rule that all turning traffic must yield, although some jurisdictions may have such a specialized rule.
the person who turned is at fault because when you are turning you are to yield to any other traffic
It depends on who had right of way.
Bikes and pedestrians always have the right of way [providing they are proceeding in conformance with the traffic laws]. Most likely the vehicle will be determined at fault. There have been some rare cases in which a bicyclists or pedestrian have been assigned some contribution of fault.
The car who hit you
It would be the fault of the truck unless the vehicle struck can be determined to be at fault for a lane violation.
It sounds like you violated his right of way and turned in front of him. From the limited description, I would ticket the driver turning.