do not want PDF to open in browser

You would have to do this with a server-side script; such as, PHP or ASP.net; but, it depends on your server's OS language

Example: ASP.net (C#):

try {
  Response.ContentType = "application/pdf";
  Response.AddHeader("content-disposition", "attachment; filename=" + FileName);
  Response.WriteFile(FilePath);
  Response.End();
} catch (Exception Ex) {
  Err.Clear();
}

You can't. It's up to the user how the file is going to be opened/viewed on their machine. The best you can do it recommend to them to save it instead of opening it inside their browser window (or you could place the file in a zip archive, to force them to first save it locally and only then open it).