The Scottish Section of this project is still blank. Here is a proposal to fill it:
1. Scottish women did not generally use married names before about 1600 (when they began copying the English about the time the Stewarts succeeded in the Tudors in England). The custom of using married names began with the nobility and spread downwards. In some rural parts of Scotland, married names did not come into use until the 19th century.
2. In Scotland territorial designations are part of the surname. The surname, including the territorial designation, is properly used by the head of the family, his wife, oldest son, and all daughters. Younger sons use the surname alone, unless they acquire their own property. Look at primary sources to determine whether someone used a territorial designation; & remember that a place name is only a territorial designation when a person is "of" a place. If they are "in" or "at" then it's a mere description of residence.
"of that Ilk" (Ilk is always capitalized) is a territorial designation that means "of the same name or place". So, the surname and territorial designation are the same. This is common when the surname is taken from a place name eg the surname Moncreiffe of Moncreiffe could be Moncreiffe of that Ilk.
It is also used by chiefs of the name who don't have a landed estate. For example, Mackintosh of Mackintosh could be Mackintosh of that Ilk.
You have to know which form the person prefers, duplication or "of that Ilk". In general, Lowland families prefer of that Ilk and Highland families prefer duplication. It’s a good idea to look up the current chief in Wikipedia then use his preferred form for his ancestors.
3. A Scottish Lord (of Parliament) is the equivalent of an English Baron. A Scottish (feudal) Baron is the approximate equivalent of an English Lord of the Manor. In other words, the titles are (loosely) reversed.
A Scottish laird is just a landowner. Laird is not a title of nobility. However, a laird might be a feudal baron -- that is, a land owner with the right to hold a baronial court (just as an English lord of the manor anciently had the right to hold a manorial court).
A usage such as "John Grant, 2nd of Freuchie" is a conversational shorthand, not his real name. His name would be John Grant of Freuchie, and he would be either 2nd Laird or 2nd Baron of Freuchie.