conscription does not exist
Conscription has never existed in Saudi Arabia.
The armed forces have increased and been modernized significantly since the 1960s, which was deemed essential to protect oil wealth. After the 1990 Gulf War King Fahd announced a doubling of the army's size and the creation of a new reserve system.
Saudi officials have indicated, on several occasions, that conscription may be introduced. There have never been any definite proposals to do so, presumably because conscription would be unpopular, difficult to enforce and liable to produce undesirable elements in the armed forces.
The government has also stated on several occasions that conscription is not needed as voluntary enlistment easily achieves the requisite number of recruits. It is doubtful how far this is actually true, in particular given the increase of the armed forces. 
The armed forces have problems recruiting the requisite number of qualified and skilled personnel able to handle complex equipment and weapons, although military salaries are on average higher than those for other government jobs and the military have been spared salary cuts that applied to civil servants.
The government tries to strike a geographic balance by attracting a representative cross section of the population. However the officer corps still seems predominantly composed of members of the Najd aristocracy. The National Guard rely on an old system of tribal levies to fill ranks, and guardsmen are mainly recruited from a few of the Najd camel-rearing tribes.
The forces rely heavily on foreign personnel: there are about 15,000 Pakistanis in the armed forces and a considerable number of officers from other Muslim countries. 
2 Conscientious objection
The right to conscientious objection is not legally recognised. The government stated in 1990: "There is no obligatory military service for the citizens of Saudi Arabia; therefore the subject matter of 'conscientious objection to military service' is of no concern to the Saudi Arabian authorities." 
No information available.
6 Annual statistics
The armed forces are 105,500-strong - that is, 0.62 percent of the population. 
 UN Commission on Human Rights 1991. Report of the Secretary-General prepared pursuant to Commission resolution 1989/59. United Nations, Geneva.  US Library of Congress 1992. Saudi Arabia - a country study. Area Handbooks, State Department, Washington DC.  Institute for Strategic Studies 1997. Military Balance 1997/98. ISS, London.  Société I3c 1988. Military Powers Encyclopedia, Volume 3. Paris.