AHey I just want to ask if I want to apply fondant on a cake, should I first cover it with buttercream? And can I let it cool in the fridge for the next day and then cover with fondant?

Yes, definitely use buttercream, but I don't wait long to cover with fondant.  The idea is for the buttercream to bond the fondant to the cake and if you wait too long and the buttercream "skims over" the fondant won't stick to it.

from a hobby baker--I crumb coat with bc and have let my cakes sit in the fridge for days, take them out and mist lightly with water then cover with MMF. I have heard rave reviews about covering with genache instead of bc. It is widely used in the UK. I am now trying chocolate genache but will refrigerate the same way, brush lightly with water as in the Michele tutorials, and then cover with MMF. A cold cake works best in this case.

AThank you! This really helps!