The length is relatively stable; almost all expansion and contraction happens across the width. The change in dimension is proportional to changes in moisture content. There's no way to accurately anticipate how much the flooring will expand, or even whether it will expand at all, without knowing both the current moisture content and how it will change.

If the flooring was acclimated to the house before installation then you shouldn't have a problem. The Wood Flooring Manufacturers Association installation manual suggests storing flooring in the rooms where it will be installed for "4 to 5 days or more" before installation.

Trimming away a bit of drywall before installing baseboards sounds like a decent way to provide some clearance.

It also depends upon the species (some woods expand and contract more than others) and how the wood was oriented in the tree. The general rule is that wood expands and contracts more around the circumference about twice as much as it does radially. This is why when you see firewood, it generally has a pie-shaped crack in it -- if it shrunk the same in both circumference and radius there would be no differential contraction.

For jatoba, "Shrinkage green to ovendry: radial 4.5%; tangential 8.5%; volumetric 12.7%-values are low for a wood of this density."

Here is a link that might be useful: http://www.jandclumber.com/JatobaHardwood.html