If I kick the ball into the opponents hand, do I get a free kick due to hand-ball by the opponent? Can I keep on doing this until I'm right in front of their net?
A player only commits a handling offence if they deliberately handle the ball (this excludes the goalkeeper handling the ball within their own penalty area). This includes any part of their arm as well, and not just their hand.*
Generally, if a player's arm is in a natural position (usually down by their side, or reasonably raised when jumping for balance), and they do not have a reasonable amount of time to move it out of the way, no offence has occurred, as they have not deliberately handled it.*
If their arm is in an unnatural position (outstretched), it's most likely there to make them bigger, and hence to deliberately handle the ball. If a player has their arms out wide for no good reason, and you kick the ball into them, then yes, they have committed a handling offence.
As this is a relatively rare occurrence, most of the time, when you kick the ball into a player's arm/hand, particularly from a short distance, no offence has occurred.
* - p. 119, 2014/15 FIFA Laws of The Game
In determining whether or not a player deliberately handled the ball, the referee has several considerations: Movement of the hand towards the ball (not the ball towards the hand); Distance between the opponent and the ball (unexpected ball); Touching the ball with an object held in the hand (clothing, shinguard, etc.) counts as an infringement (considered an extension of the hand).