Added two new methods:

InsertList(List list, double fontSize)
InsertList(List list, System.Drawing.FontFamily fontFamily, double fontSize)

and a new example of usage: DocumentsWithListsFontChange();

Thanks to those 2 methods you can easily set font family and font size when inserting new lists.

DocX/Container.cs

         {
             foreach (var item in list.Items)
             {
+              //  item.Font(System.Drawing.FontFamily fontFamily)
+
+                Xml.Add(item.Xml);
+            }
+
+            return list;
+        }
+        public List InsertList(List list, double fontSize)
+        {
+            foreach (var item in list.Items)
+            {
+                item.FontSize(fontSize);
                 Xml.Add(item.Xml);
             }
+            return list;
+        }
 
+        public List InsertList(List list, System.Drawing.FontFamily fontFamily, double fontSize)
+        {
+            foreach (var item in list.Items)
+            {
+                item.Font(fontFamily);
+                item.FontSize(fontSize);
+                Xml.Add(item.Xml);
+            }
             return list;
         }
 

DocX/DocX.cs

             list.Items.ForEach(i => i.mainPart = mainPart);
             return list;
         }
+        public new List InsertList(List list, System.Drawing.FontFamily fontFamily, double fontSize)
+        {
+            base.InsertList(list, fontFamily, fontSize);
+            list.Items.ForEach(i => i.mainPart = mainPart);
+            return list;
+        }
+        public new List InsertList(List list, double fontSize)
+        {
+            base.InsertList(list, fontSize);
+            list.Items.ForEach(i => i.mainPart = mainPart);
+            return list;
+        }
 
         /// <summary>
         /// Insert a list at an index location in the document.

Examples/Program.cs

             HyperlinksImagesTablesWithLists();
             HeadersAndFootersWithImagesAndTables();
             HeadersAndFootersWithImagesAndTablesUsingInsertPicture();
+            DocumentsWithListsFontChange();
 
             // Advanced
             Console.WriteLine("\nRunning Advanced Examples");
                 Console.WriteLine("\tCreated: docs\\HyperlinksImagesTablesWithLists.docx\n");
             }
         }
+        private static void DocumentsWithListsFontChange()
+        {
+            Console.WriteLine("\tDocumentsWithListsFontChange()");
+
+            // Create a document.
+            using (DocX document = DocX.Create(@"docs\DocumentsWithListsFontChange.docx"))
+            {
+
+                 foreach ( FontFamily oneFontFamily in FontFamily.Families )  {
+
+                 System.Drawing.FontFamily fontFamily = oneFontFamily;
+                double fontSize = 15;
+
+                // created numbered lists 
+                var numberedList = document.AddList("First List Item.", 0, ListItemType.Numbered, 1);
+                document.AddListItem(numberedList, "First sub list item", 1);
+                document.AddListItem(numberedList, "Second List Item.");
+                document.AddListItem(numberedList, "Third list item.");
+                document.AddListItem(numberedList, "Nested item.", 1);
+                document.AddListItem(numberedList, "Second nested item.", 1);
+
+                // created bulleted lists
+
+                var bulletedList = document.AddList("First Bulleted Item.", 0, ListItemType.Bulleted);
+                document.AddListItem(bulletedList, "Second bullet item");
+                document.AddListItem(bulletedList, "Sub bullet item", 1);
+                document.AddListItem(bulletedList, "Second sub bullet item", 1);
+                document.AddListItem(bulletedList, "Third bullet item");
+
+                document.InsertList(bulletedList);
+                document.InsertList(numberedList, fontFamily, fontSize);                              
+                 
+                }
+                // Save this document.
+                document.Save();
+
+                Console.WriteLine("\tCreated: docs\\DocumentsWithListsFontChange.docx\n");
+            }
+        }
         private static void AddList()
         {
             Console.WriteLine("\tAddList()");