It doesn't LOOK like your tree is in any immediate danger of expiring, but.

If you trim it makes the plant branch and produce more inches of wood.

You can shorten it by cutting half off. Most important first you have to thin it,and then prune it.I would prune and thin in the Spring not Fall,but is still up to you. Raised bed is a very good ideea.

Yes, you can add some soil to raise the bed. You have plenty of time. Major pruning should be done in the Spring, before tree breaks dormancy. You will also want to do this, gradually, over a number of years. Even if you screw up and I am sure you will not the tree will put out so much new wood that you will never know within a few seasons.

Figs are one of the few trees that can be drastically pruned back, with few worries. Apr 15, DO NOT prune anything until the tree has woken and leaked out completely. This way you have an idea of what to prune.

The difference between what a plant is and what it could be is described as lost potential.

Also, your Celeste need not be pruned at that height. Mine are 11 feet tall and 7 feet wide and I only prune the inward facing branches to open up the tree a bit. I just uncovered mine and this is what they look like.