Hunter Thief Trader Job Questions

[PureBreedHybrid]

Alright, i've experienced every class so far, im wondering:
1. once you level up a class, are there any advantages?
2. Is there any COMBAT upgrades, such as more strength?
3. Will leveling up 1 skill decrease another skill or decrease combat advantages if the are?

[Sp@rrow]

1.traders have better def against thieves.hunters are stronger against thiefs.and thiefs are stronger against trader and thief
2.No

[PureBreedHybrid]

i already know what each class fights against, and you just contradicted yourself on th first point