According to the information I have, the riser is PCIe 4.0. However, according to the manufacturer, the riser works with PCIe 5.0 ×16 with RTX 50 series GPUs: HYTE confirms its PCIe risers are "fully compatible" with RTX 50 series GPUs at PCIe 5 speeds.

Yes, that works. Siehe: https://gzhls.at/blob/ldb/9/f/5/3/85ac2ac9c980d9819ad951b1bbd96cbc4c14.pdf

Yes, you can install a 240mm AIO in this case. The side mounting supports radiators up to a size of 280mm, which also includes a 240mm AIO.

Yes, it has filters at the top and bottom

Yes, even the NH-D15 fits into this housing.

According to our information, the "PCIe 4.0 riser" cable required for vertical installation is included in the scope of delivery.

It includes a 120-mm fan (1300 RPM) which is mounted on the rear side.

Yes. Pretty much everywhere

Yes, up to a maximum length of 224 mm without any problems. I have installed a be quiet! Dark Power Pro 11 1200W in this enclosure. Greetings