in reply to your questions brother:
1. Yes, brothers and sisters of a chapter are able to vote on the admittance of both male and female pledges.
2.Yes, brothers and sisters are able to vote for both directors of fraternity and sorority affairs. The elections are done during national conventions but only chapters with recognized fraternities and sororities may have brothers and sisters that can vote. (i think a chapter may send 4 voting delegates: 2 brothers and 2 sisters)
To expound on this would also answer your third question: A chapter needs to have a minimum of 15 initiated members (regardless of gender) to be chartered.
Once chartered, a chapter's fraternity needs a minimum of 15 active brothers to be recognized. (Same requirement for a chapter's sorority)
Should a brother attend a national convention yet his chapter fraternity is not recognized (because of lack of brothers) yet the sorority is recognized because there are more sisters, he would not be able to vote. Only the sisters of his chapter would be able to vote. But if both the chapter fraternity and sorority are recognized, brothers and sisters of that chapter may vote.
4. I think there are schools with chapters composed only of a fraternity or sorority because the school is an all-male or all-female school. However, such chapters may welcome students (regardless of gender) from other schools without existing chapters who want to pledge. The existing chapters "adopt" these pledges to be able to initiate enough members to have a new chapter started at a different school.
For example, Chapter X has a fraternity but no sorority (because the school is all-male) may have female members in their rosters (females from another school without a chapter who have pledged and have been initiated in Chapter X)
Only if the females of Chapter X reach the minimum number is the all-male school chapter's sorority recognized.
These sisters of Chapter X may then start their own chapter in their own school.
5.Today, a chapter's fraternity and sorority (recognized or unrecognized) share equal power and responsibility in the chapter. The chapter is recognized as one unit. All members of a chapter, regardless of gender are recognized as one. it's very unlikely that a only a chapter's fraternity (or sorority) would be suspended. It would be the entire chapter that would be suspended.
