By the way, if we gather fun tokens on freebitco, do we also get interest on them as well? and if so, the same percentage 4.08%?
According to the website, one could earn up to 25% APY on Fun tokens if he or she bought and staked it...
It's 25% but only if you lock them for the entire year (365 days):

-15 days 5%
-30 days 10%
-90 days 15%
-180 days 20%
More tokens and more days will grant more WoF spins over the holding period. I guess it's easier to visit freebitcoin and the "Premium" tab, there is all the info about FUN tokens and it's perks.