First off "RoSi3_RoSe" had a couple of adamant points here but it's also flawed a little- Daryl(guy with bow) and Glenn (young man) are decently deep in the woods to the side of the horde, where Randall (the guy who the group had prisoner) was killed by Shane (psycho guy) to get Rick(leader/father) away from everyone else so he could kill him. (I will comment about how mess up Shane is in a second)
Randall was turned into a Walker because his neck was snapped by Shane, there are no bite marks on him (We are to assume, especially with Shane's turning that it's air born to anybody dead now) but Randall was quickly killed by Glenn slamming the curved blade into his skull.
As for Shane he was killed by Rick when they entered the field. Rick stabbed Shane in the diaphragm (muscle that 'holds your lungs') and by how quick he died along with the blood he was drowning in, Rick punctured Shane's lung(s). Shane's weapon discharged which is what started to draw the walkers attention, Rick and Carl do not notice the walkers mainly due to distress and the walkers are behind a hill emerging from the woods.
You are correct is saying that open air shots echo louder than just a couple feet from the ground, not a a whole lot but still a little louder.
The fact that Rick touched Shane's blood shouldn't effect him. If you remember Andrea held her sister and was covered in her sisters blood for a long time even after she turned.
And yes Shane deserved what he got. The guy wasn't a great guy to start with, if everyone recalls the first episode and how he talked about his ex. He was a decent guy, one who broke under the pressure of having a relationship snatched away from him.