Its true this site is Free, but if you want to compete, well, that's
another story. First off, understand the difference between Credits, Levels and Points. You can also learn more in the FAQ Home and Getting Started over there--->
Generally,
Credits are used to buy equipment and balls that are unlocked in your Level. You can also use Credits to enter pay tournaments and to buy other stuff. You can buy Credits and you can earn Credits in tournaments. You can also receive Credits by participating in offers such as the surveys you mentions.
The Level you've attained will determine what equipment is unlocked. The higher your level, the more and the better equipment is unlocked, and better virtual equipment you have makes playing this game much easier. Levels are attained by earning Points along the way.
Points are earned by playing the game. You can earn more points by playing everyday, completing rounds and in other ways. There is also a virtual boost drink call XP available that can help you earn points faster which can move you to higher Levels quicker.
Joey