My experience with the walmart ficus is that they are generally bulletproof.
And, yes, I killed all of mine but I know why: they were in a room too cold for them this winter.
However I bought a retusa (same as you) 2 years ago, re-pot it immediately and start to mess with it close to immediately too: I pruned it, chopped some branch and put it in a tent because I was trying to get aerial roots, then chopped the base of the tree because I didn't like the S shape it has, plant the top part in a pot where it rooted and so on...
During all this time and up to the cold of this winter my tree was doing perfectly well.
So I'll say: whatever you have in mind, go for it.
And also: I won't worry too much about the spots on the leaves, they look perfectly healthy otherwise and (once again my own experience speaking) Walmart ficus have a way to tell you they notice the environment has changed. Frequently their leaves turn yellow and fall (while looking perfectly healthy on the other hand) for a while and then the tree goes back producing new ones. But brown spots and tips are frequent too.
An alarming sign would be if the leaves start to become dry and crispy, or wrinkly, as long as they look like yours (I'd say fatty and waxy) it should be fine.