Hi,
I have Samuel Shaw and Nicholas Laing in my tree. Samuel (1785 - 1865) is my 1st cousin 6 times removed.
Regarding the different birth dates, most churches recorded the date of baptism. Some also recorded the date of birth. Baptisms can be years after the child's birth. Also, ministers in Scotland were not required to record the birth/baptism. It depended if the minister could be bothered to write it down.
Tom