I have always viewed
freerolls as the playground in which you can learn, experiment and develop your game.
Profit wise, its not happening unless you are extremely good and have the time to devote to such tourneys but some do and some have good success at this, it obviously depends on platform, type of FR and if you are lucky enough to be part of something like CC, you can do really well.
Shopping around for FR passwords can be easy and then less so - again it depends on so many variants with field size being the biggest challenge.
Several years back i used to turn a decent profit from certain sites and then it went boom and now numbers are huge and prizes are much lower.