1. Tools | Change Working Time...
2. Click on "new"
3. Create new calendar "July nonworking"
4. Select the dates that you want as "Nonworking" and click on the "Nonworking" radio button
5. Click OK.
6. View | Gantt
7. Format | Timescale and click on the Nonworking time tab.
8. Choose the "July nonworking" calendar
You can still schedule non-factory tasks during that timeframe.
If you want to force all tasks to be "non-schedulable" during that timeframe then Project | Project Information... and set the project calendar to "July nonworking".
If you want to force specific tasks to be "non-schedulable" during that timeframe then double-click each task, click on the Advanced tab and set the calendar to "July nonworking".
Excellent granularity: the Gantt chart, or the project or specific tasks or a combination of those choices.
No: you cannot eliminate the display of Saturday and Sunday.