While I agree with #2's implication-- that being UA doesn't fly FRA-PDX-- I'll side step that for a moment..
To me, I think you've got a legitimate issue if you were in fact "pushed" as I don't think that's ever appropriate for staff *or* passengers to do unless there's some extreme situation like a true emergency or the like.
Otherwise, I expect that everyone essentially keep their hands off other people.
"We tried to get to our seats after finally being allowed to board, only being pushed around as the attendants were serving the business class travelers their drinks"
==> This sounds like that time period before take-off when Economy is still boarding but premium cabins are also getting their pre-departure drinks and services.. If so, I can see how this happens as there's a lot of people moving around in both directions..
That said, I'd still expect a basic level of courtesy in that if someone "ran into" someone else-- regardless if that was a passenger or crew- that there would be the common courtesy acknowledgement.
"... One meal and one round of liquids offered during the entire 12+ hrs flight. "
==> Almost all carriers do scheduled 'water runs' thru the cabin at some point during the times between meal/snack services.. Some do it more often than others, but almost all do it (in part as it also allows the crew to see if there's any issues or problems brewing).
Therefore, I'd be very, very surprised if in fact there was no 2nd or any later beverage service offered after main meal service ended, as that would mean essentially that on a sector of about 10h:30m to 11h:30m of total length (10:30 to shorter legs like to SEA and 11:30 to cities a bit longer like SFO) that the cabin went without any beverage offering for the last 8h:30 to as much as 9h:30m.
Sounds like there might be some issues here.. I'd need to see exactly what that pushing at the airport was and what the case was on-board as I can see this is several different ways.. However, the idea that no services were offered after main meal on what is/was a 10h+ sector, I personally think is not the reality.