Post of First Minister is for the 4 years between Holyrood Elections
5 year
There is no set term. Stephen Harper will remain the Prime Minister of Canada until he resigns or the Conservatives lose government.
The deputy Prime Minister is a post that is the gift of the Prime Minister and the UK currently has no DPM, the last DPM was John Prescott, who was in office while Tony Blair was PM.
26 but some served more then 1 term.
The West Indies is a general term which refers to many different countries in the Caribbean Sea. It is not one country. As there are many different countries in the West Indies, there are many different prime ministers.
There have been 27 different men who have served as Prime Minister of Australia. Some of these have served more than 1 term, on different occasions.
New Zealand has its elections every 3 years obviously meaning that a New Zealand Prime Minister has a 3 year term and maybe they are lucky enough to be re-elected for another 3 year term. However, many times in the past, New Zealand Prime Ministers may have served far less than a full term, or a full term and part of a new term. See the related question.
The British Government has to call a General Election every four or, at the maximum, five years. British Prime Ministers do not have term limits as US Presidents have, they can remain in power for as long as they are supported by public opinion and the confidence that their own party has in their leadership. Margaret Thatcher was in power for so long because she had the majority support of the Conservative Party, and also because the opposition Labour Party was weak and in disarray at the time. She was finally forced to resign in November 1990 because of the overwhelming opposition to the Poll Tax (basically, a tax for a person's very existence!) both from the British public at large and from within her own Party.
An aube is an obsolete term for an alb, a long white robe worn by priests and other ministers.
There is no restriction on the number of terms a Prime Minister can serve, or the duration of each term. A Prime Mimister remains in office for as long as his party is in power while he is its leader, regardless of how many elections occur during that time. It is quite common for Prime Ministers to win several electoral mandates during a term in office. Notably, Sir John A. Macdonald won four electoral mandates during his second term in office, and Sir Wilfred Laurier did the same during his term. Several Prime Ministers, including Sir John A. Macdonald and Sir William Lyon Mackenzie King, served multiple terms as a result of regaining power after having lost office. The most recent Prime Minister to do so was Pierre Trudeau.
It's unclear whether you mean after you have stopped being Prime Minister, or as soon as you become Prime Minister. If you mean during the term of a Prime Ministership - there are a whole lot of things that you can't do, according to whatever national constitution you're talking about. If you mean, after a Prime Minister finishes his or her term - there is very little restriction on what you can do, since you are simply a private citizen. Many countries, such as Australia, pay former Prime Ministers' travel and office allowances, so they can do things like compile memoirs and give speeches in various places. Former Prime Ministers will sometimes make contributions to politics, but in general they are expected to stay of day-to-day political questions. Many former Prime Ministers make careers in other areas such as business, for example.
3-5 years long