B0102-03903-BK 4PCS Full Door Panel with Sliding Vented Window

Is this for all 4 full doors or 2?

4 full doors, including 2 front doors and 2 rear doors.

All hardware included?

Yes, the hardware are included for installation.

Can the upper part be removed to make them half doors for the summer months?

No, it could not. But all four doors have sliding windows that could be opened for ventilation to cool down in summer and closed to block cold wind in winter.

How to install the doors?

Here is the installation video for your reference.