I think that the Taylor sin-binning was harsh, but I can see why the referee gave it. I said to myself when I saw the first replay that it looked like he instinctively stuck his hand out to block the ball. So hard to tell though, so I still think it was harsh.
On the grounding of the ball, the referee gave the try so he had clearly seen the grounding. If the on-field decision is a try then the TMO has to see clear evidence that it shouldn't be a try to reverse the decision, there was nothing clear so they stuck with the on-field decision.
If the referee had said that he couldn't see if it was grounded properly and asked the TMO to check the grounding, or if he had said "try, yes or no?" then the decision may have been different as the TMO could say there's no clear grounding and not award the try.
This is the correct way to do things, the referee is still in charge and should take responsibility and make decisions, so they should, wherever possible, make a decision and ask the TMO to check if there's any reason it should be over turned rather than going to the TMO to get a decision made.
The final pass to Earls certainly was caught in front of where it was passed, but that doesn't necessarily mean it was a forward pass according to how the laws are interpreted at the minute. It is currently interpreted by looking at the hands of the player passing the ball and not the motion of the ball. If the hands pass the ball backwards it is considered a backwards pass, even if the ball travels forwards. If a player is running forward, the ball has forward momentum, so even if it is passed backwards it can still travel forward because of its forward momentum, in order to give the benefit to attacking teams and try to boost try scoring, this forward momentum is allowed if the player passes the ball backwards.
To me it looked like O'Mahony's hands were passing the ball backwards, so even though the ball travelled forward it is classed as a backwards pass.