Do lightsabers absorb any of the energy shot at them by a blaster, or is it all deflected away?
Some of the energy from a blaster shot is reflected, and some of it is transferred to the light saber as kinetic recoil. This is subtle but visible in Return of the Jedi.
How much energy goes into the recall, and whether there are any other modes of energy conversion besides reflection and recoil, is unclear.
Simply, I would say that it deflects most "bullets". Most "bullets" are a single bolt, meaning that what we see bounce off the lightsaber appears to be the same. Therefore, I would assert that it is all deflected away.
Well, you got to remember that lightsabers and blasters are pretty munch laser plasma weapons incased in a forcefield. The problem here, is if you where just dealing with light the answer would be easy, but you are also dealing with a forcefield.
If you're just dealing with light blasters that have the same color and chemical, the lightsaber would absorb the Blaster fire, which is what happened in Star Wars: A New Hope. The Stormtroopers where shooting blue blasters at the lightsaber and Luke's lightsaber was absorbing it. I think it may have to do with the color of the light more than anything.
Light rays of the same color will be absorbed by the object's color, but the rest of the colors would be reflected. This is why you can see a blue circle, a yellow box or a red square. The standard RGB which represents the 3 main colors and light ranges. In that movie example the reason the blaster fire was reflected is the lightsaber was green and the blaster color was red. I think the strength of the force fields also applies.