Both answerable, breathe :)
Sequence: crumb-coat and ganache the cake, then chill it FIRM - 15 minutes in the freezer does it - and drape the fondant over the set, cold coat. Fondant over soft ganache slides and bulges; over a firm coat it sits clean and smooths beautifully.
Monsoon fondant absolutely works with one ingredient: tylose powder (gum tragacanth). Knead a little into the fondant AND use it in your dusting medium instead of pure cornflour - it firms the fondant faster and fights the sag. Always knead fondant thoroughly before rolling, even a fresh pack.
Keep the finished cake in the driest room you have, AC if possible, and resist refrigerating a fondant cake uncovered - fridge-to-humid-room condensation makes fondant weep. Cold cake, firm coat, tylose in the mix. Your small wedding will hold.
