1: In late game you will have a chest ,and *SPOILED* you can unlearn your skill (mean you pay some golds , and all your skill will be unlearned) so don't worry , just put 1 or 2 points in what skill help you carry more stuffs
BUT to get there you have to be at level 18 or so (I mean that will take you a lot of time to get to that part)
2: My character is not a ranger
I do remember there is a skill which allow you to get to the enemy closer than normal without undetected
3: Shield is one of the most silly things in this game LOL