Answer 1

An attribute in HTML is any valid name/value pair for that element. HtmlElement exposes only those attributes that are common to all elements, leaving out those that only apply to certain types of elements; SRC is a predefined attribute for the IMGtag, for example, but not for the DIV tag. Use GetAttribute and SetAttribute to manipulate attributes not exposed on the managed Document Object Model (DOM).

GetAttribute and SetAttribute are case-insensitive.

More on the link below:
https://msdn.microsoft.com/en-us/library/system.windows.forms.htmlelement.getattribute(v=vs.110).aspx