If the minyan doesn't have enough time allotted for Selichot to finish everything listed in the Selichot book for today, so you need to cut some parts out, what are the rules of priority for what should be cut out first, last, or never?
The least I've seen is Ashrei, kaddish, (don't remember about the pesukim), s'lach lanu-intro to 13 midos-13 midos until lechol korecha, pizmon, intro+13 midos, the rest like a regular fast day (including only one ashamnu), niphilas apaim, shomer...
There are the many things that are simply Yeish Nohagim, that could be (and often are) skipped. There is also the final Keil Melekh and Hashem HaShem that according to Kabbalah and Minhag Beit El don't belong there.
However, really a competent posek should be consulted.