An introduction to Stuart architecture can be found here: http://www.building-history.pwp.blueyonder.co.u...
About the "leads" where Elizabeth and Sam spent their evenings:
Willoughby House is a magnificent house in Nottingham built by the Hon. Rothwell Willoughby (brother of Lord Middleton) between 1730 and 1740.
When it was built, the view from the roof was regarded as a great asset and walkways covered with lead were made around the edge, easy access to which was arranged by means of internal stairways. To prevent accidents, parapets were set up and the good folk of the 18th century -- and even earlier -- used to spend a good deal of their leisure on these "leads" as they called them. Readers of Pepys Diary will find references to evenings spent upon the leads engaged in singing and talking.