A few things to add to this FAQ:
Each poll question can have a maximum of 255 answers.
On a poll question with a large number of answers, only the first 88 selected by a user will be listed in the results.
A poll cannot have more than 255 questions.
This was tested here: http://www.livejournal.com/community/snafuwaffle/2809.html (i specified 1200 questions and 255 went through.)
And here: http://www.livejournal.com/community/quothtest/10748.html (over 300 possible answers were specified and only 255 went through. additionally a poll taker checked all the checkboxes and only the first 88 were listed. if a number (like 3) was deselected then numbers 1-2 and 4-89 showed up as selected.)
thought it'd be kinda cool to have those things in the FAQ. :)