Thank you for writing and asking about HyperNext.
My question is: can HyperNext Studio co-exist in the same computer with:
a) Visual C++ Express 2005 or 2008?
b) Java NetBeans or Eclipse?
Yes, but HyperNext cannot interface with those languages / IDEs.
By the way, although you didn't ask, HyperNext does not need DOT NET installing.
My second question is: can HyperNext access Window APIs (especially MIDI and graphics)?
Unfortunately the current version of HyperNext (V3) does not allow the programmer to interface with Window APIs.
I have some plans for this in version 4.x but its still under development.
HyperNext does have some commands for accessing MIDI and graphics( canvases and sprite engine) but clearly not as good as direct calls to APIs.