bsp,
time depends on what you want to put into it. I serve on the House Corp. and we meet 2 times a year officially. Alum Asso. meets monthly for social, but of course the Chapter is discussed since we are trying to build a new house. Keeper and finder of emails for the Alums.
Distance means a lot, are you near the chapter?
Are you currently active with the chapter.?
Advisor is exactly what says, advising the chair of the active chapter of that position. Can be done in person or via phone.
I for one would not give a second thought about advising as have been doing it for a LOOOOONG Time!
You can put as much time as you feel you can.
Just say GO!