Illustris usage

I'm trying to tease some data out of Illustris, and am
having trouble parsing the data access specifications[1].

For instance, about one-fifth of the way down, it says
(in part):
The general unit system is kpc/h for lengths,
10^10M_Sol/h for masses, [...]

The two meanings for "h" for which I'm aware are "Planck's
constant" and "hours". Obviously, neither one of those makes
any sense in this context.

Where can I find out what "h" means in this context?

Also, I'm going to need to follow the histories of various
subhalos. In the section on Merger Trees, it says:
The number inside each circle from the figure is the
unique ID (within the whole simulation) of the
corresponding subhalo [...]

Is this "SubhaloID"? If I find a way to extract data about
SubhaloID == 42 (for example) from each snapshot, will I be
following a single subhalo through time?

Is there a similar field for halos? I'm trying to follow the
changes in a galaxy after its capture, and I think that I'll
need to be able to find out things like the mass of the halo
that captures it.

This page is quite comprehensive, but that makes it overwhelming
for somebody who's never used Illustris before. Is there a
novice's introduction or some documentation that explains the
documentation?

I'm sure that once I get a handle on their conventions, I'll
be able to bootstrap pretty quickly. It's getting up the
first part of the learning curve that has me stumped.

Thanks for any help that you're willing to provide.

[1] http://www.illustris-project.org/data/docs/specifications/

--
Michael F. Stemper
Deuteronomy 10:18-19