Crumb coat before fondant - please help

[AnxiousFTM]

I’m making a birthday cake for my daughter and really need help as I’ve never done this before. Its a 4 layer sponge cake with jam and buttercream between the layers which I plan to put fondant on with various decorations I’ve bought.
So I’ve currently made the cakes which I plan to wrap up shortly and decorate tomorrow.
From what I can find I need to put a very thin later of buttercream on the cake (crumb coat), then how long do I put this in the fridge?
Then do I do another thicker coat of buttercream to put the fondant on? Does this 2nd layer of buttercream need time before I put the fondant on?
Also whats the best way to stick decorations to the side of the cake? Is it more buttercream?
Will the cake stay fresh if its left uncovered once its decorated?
Thanks so much in advance

I crumb coat then put it in the freezer for 10mins so if you’re doing the fridge I’d give it an hour
Then I’d go on with your fondant and I’d stick things on using buttercream or a thick mix of icing sugar and water
It will stay fresh for a while, but if it’s going to be more than a few hours I would cover it

When you crumb coat be sure to dip your spatula or knife in hot water and then dry it. It makes buttercream easier to spread.
Get buttercream nice and even.
I literally use a spirit level ( kept for cakes only).
You can wash a light one and place it on kitchen paper across cake.
Refrigerate 1 hour.
My crumb coat is normally thick enough for fondant.

You may need to slightly dampen the crumb coat before putting fondant on if it's very dry from fridge.
How good the end product looks will depend on how flat and even your cake is.
How well you apply the fondant.

I usually measure the cake with a piece of ribbon or string and then place that length on the fondant so I know I've rolled it big enough.
Smooth the fondant with the flat of your hand and rub it until it is shiny.

Watch some you tube videos. It will help.