Every level gained gives 5 stat points to spend on STR, INT and DEX.
The auto-distribute button only works until you meet the requirements of the rank test.
Each class has its own formula for every combat stat: the server defines which base stats count (STR, DEX, INT) and applies a piecewise line whose slope changes past certain stat values.
For example, the Wizard's magic attack depends only on INT and the Warrior's attack only on STR.
The client shows as percentages the resistances to critical rate, critical damage, unmovable, down, knock back, stun and skill amp.
See also: In-game help: Growth · In-game help: Character Information · Stats
Data from the Cabal Latino server and client (EP33).