This is a question better asked and answered on the Adenium forum. http://forums.gardenweb.com/forums/adenium/

Hi! I don't have any rooted cuttings but thought I may be able to pull some from a root ball, but turns out we're (my grandmother) is not yet ready to transplant her fig. But if we end up doing that this spring, I'll get back to you. Meanwhile, I'm going to research rooting cuttings!

Your trees were pruned to be trees, not bushes. They appear to be at least 3 years old. Really hard to tell age because some trees are more vigorous than others. For instance, I had a Fig in a pot for two years, then planted it in ground. Suddenly that little thing trippled in size and it's trunk(s) became thick. Now it's huge, and I think nobody would guess it's only 4 years old. It's got about 15 figs per branch and there are a lot of branches. Every year, as your trees grow older, they will put out more figs. Really hard to know what a potted fig can produce. A lot depends on variety too. I don't have LSU Purple, but my Celeste is very productive. At 2 years old, it has about 20 figs, but it's still in it's pot and has worked it's way into the ground. This year when it's dormant, it will be planted in ground. You'll just have to be patient and wait. The figs will come. We get mild snow fluries here in winter maybe for a day or two, so planting in containers isn't important, but many who live where it snows have to bring their containers in for protection from freeze. I know you rent so want to take them with you. Good plan! :-)

A great soil will be just fine and the important part is giving your Fiddle Leaf Fig plant time to to allow the roots to take hold. You can read more in this posts here. Fiddle Leaf Fig Propagation in 6 Easy Steps