I have a cake that i was asked to do for my churches 15th anniversary. this is what i was thinking and then i will ask my questions.

It will be for 150+ people, and made out of a white chocolate cake with BC filling with fresh straw berries and covered in BC. and maybe fondant

It will be a 4 tier cake ( still working on the size of each cake)

I am going to start it off with a square then top it with 3 rounds and it will have A RKT topper made to look like a rock and down the back it will have "Oil"flowing from the rock down the back if the cake( like a water fall).
The square bottom will be made to look like the church and on the front of the rounds it will have the words FATHER SON RELATIONSHIP(One word on each round).

Psalms 133 is where we are pulling the design from.

Now my questions:
1. How would you make the look of oil(like vegetable oil) flowing down? I am not sure if i should use piping gel or bc or steamed fondant to get the best look!
2. With the fresh berries how long can this be out of the fridge for? I am wanting to do Fondant covered but can't put it in the fridge. Is there a fondant that can do in the fridge?

3. what borders would you use? I am still new at this and looking for something nice and different.

Any tips you can give would be great this is my biggest cake that i have ever did so i am very nervous about it.

Maybe I'm wrong, but I've seen people put fondant cakes in a cooler/fridge to keep chillled.

Also, you should soak your berries in sprite or lemon juice before you put on the cake. This will help them keep their form and freshness for longer. The acid does this for the berries.

And in my opinion, "water" looks best use piping gell is used. I personally like when people put a colored bc or anything colored underneath the clear piping gell because it looks more realistic than just using a colored piping gell. Kinda like this: http://www.cake-decorating-corner.com/waterfall-cake.html

I would go w/ piping gel for the oil. I use Satin Ice fondant and put it in the fridge all the time.

I am getting really nervous to do this cake, Thanks for the help