Tdp seems fine to me for psu sizing. At the end of the day the psu may have some overhead anyway. You may want to look at pcpartpicker. They provide an indication of psu capacity

Caddy or traefik or swag do this. These act as reverse proxies.

Can someone please elaborate on the differences between „ubuntu server“ and „ubuntu“? I assume it is about different packages that are (or aren’t) pre installed by default. Can I assume that either installation can be adjusted to become the other by removing/adding packages? (Apt)