Well to answer #1 and #2, use any of the 4 USB C ports on the motherboard that you want. It’s designed to be modular. As for #3 yes, there is tons of resources all over the community, just search for it.
Just uses USB-C PD. Ideally Framework recommends a USB-C PD source capable of 5A @ 20v for standalone operation, however PD sources of around 60w (3A @ 20v) should also work (but the performance may be slightly reduced).
No HDMI directly on the board. The USB-C ports can carry a DisplayPort signal, which many hubs and adapters (including the Framework HDMI expansion card) will translate to HDMI to get you an HDMI signal.
I don’t think there is a single place for documentation that is specific only to the motherboard. Look at the documentation for 11th Gen DIY Laptop or 11th Gen prebuild Laptop, that of course will apply to the motherboard as well. The specs pages, the knowledgebase, and the guides. If you have certain questions, the forum community can likely help.