web page design and coding

This may be a simple question.  But it is important to me.

This is for web site, not a desktop application.

Developers know how to do the coding,  graphics designer knows how to design web page in dreamweaver.  Once web page is giving to developer,  graphics desiger can not edit it any more because they do not know how to use visual studio.

We try to separate all code into .cs file.  But the html code has to site in aspx file.

If you need to make changes to web page,  what do you do?  Do you change it in dreamweaver, merge the code, or do you let graphics designer change them in visual studio?   I know for small change, like spell error, we can do it in visual studio.  I am talking about relative big change.

How do you handle multiple language?  Do you put text in separate file?  For example, text for label.

Thanks in advance for your help.