Indeed, all that information is readily available, But it is all transcriptions and index listings.
"Working on the marriage date she should have been born about 1841". Well, too bad, but making wild guesses like that is how errors get into online trees. I even warned about this particular assumption in a post two days ago on this very thread. I have only seen a small proportion of all the marriage certificates in the Scottish records - just under 5,000 for my own family and maybe another couple of thousand for other people's trees - and the number of women who married at age 21 (let alone younger) is very low. Most were in their mid to late 20s at marriage.
Also, as I have already said upthread, I bought a copy of the marriage certificate of David Winchester and Rebeccia Ross. It says there, in clearly handwritten black and white, that David was 25 and Rebecca was 35. Yes, thirty-five years old. Not 21. This is consistent with her age in the assorted censuses and with her death aged 38.
Those extracts from assorted indexes are very useful indeed far saving time hunting down the original records. You can then go to a Family History Centre, arrange to rent one of the FHL films mentioned about, and then go back, view the films in the FHC, and make notes from it. Or you can go online to www.scotlandspeople.gov.uk and download digital images of the certificates on the spot, for less than the cost of a cup of coffee or a pint of beer each.
There is ***NO*** substitute for looking at the original documents.