It depends on if you are making a left turn at the intersection with a green arrow or not. Oncoming traffic always has the right of way unless at an intersection with a green arrow/red light.
I have always been told that the left turning vehicle is chargeable (at fault)if while turning there is an accident. In other words you are indefensible on this because to cross over an opposing traffic pattern as in a left turn, you must yield under all circumstances. The same thing applies to rear end accidents. If you rear-end someone, you are indefensible. It is always your fault. The rationale in both scenarios is that the left turner and the one behind have to wait, have to see, yield to everything and only when clear can they proceed.
It depends. I made a left turn at an intersection after my light (w/out arrow) turned red and an oncoming car did not stop. Because the other car had ran the red light he was at fault and his insurance paid for my damages. This was in California.