Is this good for 1440p gaming?

Yes, if it ships with a mid-range or better graphics card. The 8-core CPU and 1000W supply won't hold a modern GPU back. Confirm the exact GPU model before buying, since it drives gaming performance more than anything else here.

Can I upgrade the graphics card later?

The 1000W power supply gives plenty of headroom for a large card. Check the case's clearance for card length and thickness, and confirm the PCIe power connectors the supply provides.

Do I need to buy a monitor and peripherals?

Yes. No monitor is included, and no keyboard or mouse is listed. Budget for a display, keyboard and mouse, or reuse what you have.

How much storage does it have?

It has a 2TB PCIe SSD and no hard drive. That is enough for Windows and a large game library, and you can add more storage later if the motherboard has free M.2 or SATA ports.

Does it come with Windows installed?

Windows is listed as the operating system, so it should arrive ready to set up. Confirm the edition and that the license is included when you order.

Is the white case hard to keep cool?

Panoramic glass cases can run warmer than mesh-front cases. Make sure the fan layout pulls air in from the bottom or side and exhausts out the back and top.