1.In your controller code, you have to manipulate your items from the dropdownlist by testing on the string size that exceed a maxim length of chars (you should test with bigger values like "MMMMM...M") then in the end will result a
List<SelectListItem>
list ready to be used in your Model as property. Finally in your view you can render it by using
@Html.DropDownList("myDropDownList", Model.MyList, new { @class ="dropDownList" })
and by specifying a class (named "dropDownList" in my example) for styling the list with a proper font and font size at least.
2.Regarding how to show the tooltip here is the solution:
-populate in your controller a string with the text needed text to show as tooltip and add it as a property to your model;
-use this info as to show it as tooltip by using jQuery as is indicated in the next link:
Example[
^]