The CGI standard is implemented in almost all of the most commonly used Web servers. It is quite analogous to CGI serverscripts. ASP, however, is tailored to work with Microsoft's products. There are no actual requirements to the user's browser regarding the running of serverscripts. The browser should be able to handle forms, however, if you wish to send input to serverscripts via neat entry fields.
Forms is part of the HTML standard, so today most browsers can show forms.
Drawing tools which can be used include Illustrator, Freehand and Corel Draw. Illustrator, Freehand and CorelDraw have the advantage of being based on vector graphic. Vector graphic can be scaled and will after scaling keep the visual precision. Graphics from e.g. PhotoShop are bitmap based and are primarily suitable for use on screen. Agree on the maximum size with the editor.