Combat tokens/rewards can be traded, the daily mission tokens/rewards cant. I would say its worth doing the daily missions but it depends on what mob it is for that day, i wouldn't recommend going above and beyond completing a mission that is to high level/annoying. Every now and then you get a bonus mission that rewards 20 tokens in one go to which isent to shabby.
If you are looking for what rewards these two different tokens give you want to head over to the balcony @Twins, there are two NPC traders on the second floor.
If your asking about all the different attribute tokens as well those cant be traded either. 100 a tokens = 1 point in the named attribute.
Best regards
Zweshi