I think, as with all relative issues, one has to gauge more than just the words. First consideration is the individual uttering the phrase. Was he the kind of person who starts yelling "whoooo...I am soooo wasted" midway through his first beer? If so, fuck pile may be 1 beer for each person at event. If no, what about the fraternity? Is it a Delta House situation or are we talking some sort of honor society type fraternity? If the latter, fuck pile = less than LSC consumes before he heads down to the rifle range every Thursday night. If the former, fuck pile may be a very large quantity.
I guess the bottom line is that when it comes to alcohol, these terms are hard to pin down.
Now a couple, notably butt load and ass load may be indicative of a true Greek organization and I would recommend avoiding any party at their "house". I would also avoid any invitations to stay at their hotel room, regardless of how far your hotel may be.
Pant load and shit load are terms I have usually seen in association with small children or senior citizens. Once again, I would avoid situations where these terms are used. If this is unavoidable, bring latex gloves.
Metric fuck ton bothers me because as is common knowledge, only pussies use the metric system.
The terms a fuck ton and a a fuck pile sounds like something from a bad porn movie and as someone who has seen a lot of bad porn, I don't have much use for anyone or anything remotely associated.
This leaves a lot, a whole lot, a really fucking lot, a truck load, a whole bunch. I think these are pretty clear.
As someone involved, albeit peripherally, in the education of our young men and women I think you should formally request that any future references be limited to a lot, a whole lot, and a really fucking lot. Doesn't that really cover it?
Hope this helps.