If you're sugar pasting I wouldn't do two layers of buttercream, this will usually give you a bumpy finish. Just one very thin buttercream layer before the sugar paste is fine. I use trex for kneading but icing sugar underneath when rolling out.
No don't put in fridge before icing. You need to do a rough crumb coating with buttercream and can pop this in fridge but only for a few minutes. Then do a smooth buttercream coating followed by your fondant.
You can use Trex to help roll out the fondant and it won't affect the flavour. You only need a small amount though.
I'm making DD's first birthday cake (birthday Tues) tomorrow. Planning on making a madeira cake, cut into a 1 shape and iced with ready-roll fondant icing.
Is it best to chill in the fridge or freezer before decorating? And how long for ideally?
Also with the ready-roll, I've seen that it can be rolled/kneaded with grease as opposed to icing sugar, has anyone tried this? What did you use, and did it affect the flavour? I used icing sugar when I did DS's cake, but it was only for small decoration rather than covering, and it did end up with some fading where i couldn't brush the sugar away. Obviously I don't want a fondant covered cake to have that.