Yes, swapping to pre 08 keys and blocks will lift your truck an inch or so.
No, there won't be any extra wear/problems as Pre 08 rangers came from the factory setup this way. Your truck has the same suspension, just with re-indexed torsion keys
No, you won't need to change anything else. All you will need is the keys, the blocks, and a new set of ubolts.
Be sure to get an alignment afterwards.