Dont use the mod in the Ranking event, if you did, see if you score has been erased or not. If erased, that is a sign that they've caught on and stop doing the Ranking event or risk getting banned. That's how I lost my main account because I didn't think nothing of it until I got banned. I stop the Ranking event period. Not sure, if its safe to continue but mod off or not as I haven't tried.
Yes, but I only do it if the difficutly level is lower than a certain x% of my teams total EP. I'll turn on the low ATK, low DEF, unlimited BLISS (for when I need it) and let auto do the rest. The only time I turn on Unlimited Skills is to complete Limited challenges for the rewards.