A few niggly points picked up in Pam's excellent survey of the initial topic.
For those of you not able to get to Edinburgh, contact your local Registry Office to see what research facilities are available.
This applies only to Registry Offices in Scotland.
ScotlandsPeople have indexed all the parish records available and they are searchable from their site www.scotlandspeople.gov.uk
They have indexed the extant Church of Scotland and Roman Catholic registers, but not those of any other denomination.
There are many Family and Local History Centres (FHS & LHS) around Scotland
Films of the Church of Scotland parish registers (and the 1841-1891 Censuses) can be ordered for viewing at any LDS Church Family History Centre anywhere in the world, not just in Scotland.
Probate in Scotland is based on Scottish Law
There is no such thing as 'probate' in Scots Law. The corresponding process is called Confirmation. The number of wills available depends on the number of people who made a will, not on differences in the legal process to deal with them.