Can an availability range be inserted in the middle of an existing range?

Yes. Moving an existing range to the middle of another existing range with a different availability: the destination range has been split in two and the other range is included.

Is it possible to automatically adjust two availability ranges?

Yes. Moving an existing range as a partial overlap of another existing range.
→ If the two ranges have the same identical calendar availabilities, the two ranges are merged.
→ If the two ranges have different calendar availabilities, the existing range is reduced accordingly.

How is the technician's or material resources' weekly calendar determined?

In the module settings, some settings under the "Resources" grouping determine the "Week" display of the calendars.

• First day of the working week (PLANNING_FIRSTDAY): indicates the 1st day of the week.
• Number of days in the working week (PLANNING_WKNBDAYS): indicates the number of days to be displayed.
• Day start time (PLANNING_WORKBEGIN): day start time displayed.
• Day end time (PLANNING_WORKBEGIN): day end time displayed.

The "Month" view will display the timelines by day, for all days of the month, over 24 hours. It cannot be configured.

Only availabilities for which the "Copy" check box is checked are copied with the global copy action. See Calendar availability.
As regards graphical handling in calendars, there is no restriction regarding copy/cut/paste of calendar availability ranges using the keyboard shortcuts Ctrl+C/Ctrl+X/Ctrl+V.