What’s the minimum computer configuration that you can install H-Sphere to?

You can begin with Pentium II, 200MHz, 512RAM.

there any special partitioning requirements?

create at least two partitions, because H-Sphere web box requires userquota feature enabled, and it is recommended to keep user disk quota feature on a partition other than the root.

I have a big partition I want to use for H-Sphere among other things. What do I do?

You should create the H-Sphere directory in the place you want to store H-Sphere files, and create a symlink to it in the root. For example:

mkdir -p /home/hsphere

ln -s /home/H-Sphere /hsphere