Regarding the Donegal South-West by-election, thejournal.ie has this tidbit:
Polling stations opened at 7am this [Thursday] morning and remain open until 10pm tonight – though voters on Donegal’s islands voted on Monday, as is traditional, to account for any difficulty in bringing the votes to land.
The count begins at 9:00 a.m. Friday, Irish time.
The Sinn Fein candidate, Pearse Doherty, is expected to win rather easily.
A Red C poll commissioned by Paddy Power two weeks ago showed Doherty commanding a massive lead in the opinion polls, with 40% of respondents saying they were likely to give him their first preference vote, while another 17% said he would receive their second preference.
The electoral system, of course, is single transferable vote. But this election is for one seat, which means the system reduces to the alternative vote, where the quota to win the seat is 50% + 1.