I want the model to have 200,000 quad meshes. But the slider has a maximum target polygon as 100, which means 100 thousand.
Can I make it 200 (200 thousand) ?
Plus, can I use mouse wheel button to zoom in/out ?
Set the target to 50 and then subdivide the result once. Work on a clone and project the detail to the new topology.
For mouse wheel zoom, a user made a plugin here (4R7 version at post #83):
http://www.zbrushcentral.com/showthread.php?183019-quot-Middle-Button-quot-Plug-in-for-ZBrush-4R6