4:yes it is legal when the action is declared he would get -2 for option 2.
Then he would get +5 for the perplex/shield. The end result for damage is +3.
With the range the end modification is +3 is that is legal also.

5:the only Shield figures that would be required to be given a token are the ones that increased the damage. The increase range of the shield TA does nor require a token to be placed.

6. If I'm making a range combat attack agenst a Sentinel and there is hindeting terrain in between would the sentinel get a +1 to his defense thanks to the hindering terrain?

7. How would it work if there are characters instead of Hindering terrain?

Yes.

characters are ignored.