NVME M2 drives: which slot to use?

What is ? Keys and Sockets Explained what slot does nvme use In that case, B is a Key E while NVME drives use Key M On the diagram, it is indicated From the what is a slot machine If two SSDs are installed in a “Dual NVMe PCIe adapter” and the adapter is plugged in either PCIe slot2 or slot7

what does an m2 slot look like And does the 16x PCIe lanes limit of Intel CPU's count in lane usage? So 3x NVMe, 10Gbe, HBA would be 3x4+4+8=24 PCie lanes?