You can make I, L, T, and X with all possible variations from 2-4 ports basically. The above ground can do the same but throw in a single above ground port (with all possible underground variations for every single above ground rotation.)
If I remember correctly you can change the key in the settings. If not, I can absolutely set it up, just let me know. (I can look in a bit when I get some time, so whoever gets there first)
The pump reaches as far as the longest pipe, so it works for t1 up to t3 in my mod.
There’s not varying size tanks yet, those are next.
There are changeable top-up and overflow style valves (you can increment them from 10% up to 90% for both iirc), and a check valve. These are all mechanical in nature, so no actual power is needed to function.
To answer, yes my pipes return to the base one needed when mined, and can be built only using the base one by Robots for blueprints.