Here is a pic of some of us hamming it up, in a Charlies Angels pose ( we were mocking some folks)..
Note the guy in the middle with a single point sling. When he is hands free, the carbine dangles loosely between the legs in his case. To bend down, or kneel you end up with a muzzle in the dirt, and sometime a rifle butt in the chin.
I am on the right with a Viking Tactics 2 point. In this case it is slung loose, but when I completely let go, it rests across my body, allowing me to use hands, kneel, etc without issue. If I need to do something strenuous or kneel for longer periods, like working on a person, or whatever, I have the option to sling it completely behind me, or to the side, pull the strap and it is cinched down.
So here is a funny video featuring Pat Mcnamara (former CAG/Delta). While he is goofing off here, the video perfectly illustrates why the vast majority of the pros run 2 point slings.
https://www.youtube.com/watch?v=Fq-hQYcoVmwThe ease in which the rifle is situated completely out of the way while doing physical activities, as well as shooting is better demonstrated better than a few hundred words.
Reference white lights:
There is a lot you can write on the subject, I tend to prefer Surefire. Lots of ways to skin the cat, and it does not need to be uber fancy. I will take a pic after a bit of how my primary rifle light is mounted.
Also if you have the $$, a white light/laser pistol light mounted on a rifle can be a very useful tool, especially if you are shooting quickly and perhaps in unorthodox positions.