How to make my stem stronger?

This is my first Reddit post, so hopefully I’m doing this right. I have had this fiddle leaf fig since it was a foot tall. Very proud of how far it has come. I pruned it back this summer to help it produce branches. The stem is still quite narrow and would completely bend over if I didn’t have the stake. What should I do?

Also, I now have three branches from the stem. Should I prune my branches to produce more? I want it to look more like a tree.

I live in Idaho so the weather gets really cold for about six months out of the year. What can I do to help it nourish through the winter? It is very dry here.

At what point does it need to go in a larger pot?

Sorry for so many questions! I will take any help I can get!