1.The freeze-up issues typically related to graphics card and driver versions; please check your graphics card against Autodesk Certified Graphics Hardware List.
http://usa.autodesk.com/adsk/servlet/hc?siteID=123112&id=6711853
You can also try turning off ‘Use hardware acceleration for better performance’ under Options > General Settings window.
2. Fill Style is a tool that works on a Fill Library item. Thus they are two different components of Freestyle.
3.You can control drawing order by right clicking an object then selecting Draw Order > Bring to Front or Send to Back.
4.In the layer pallet, select and expand the layer you are working on, then by toggling a light bulb icon you can control a desired sub-layer visibility.
Regards,
Avto Chachava, Autodesk Product Support
Avto Chachava
Autodesk Product Support
Autodesk, Inc.