Should one use a visual editor
No. They are mostly for people that don’t want to do the hard work and create a lot of junk code. Avoid editors like dreamweaver where things can be dragged and dropped. Best way to do it is using Notepad (Windows) and TextEdit (Mac) and a bunch of stuff that are free on Linux. If you want it to be a bit more colourful you can use editors like Coda, Netbeans or Sublime Text. They help you just a bit by colour coding the different aspects of the code.
When do I use Photoshop?
Only when you need to create graphical elements that are not possible through CSS3 and HTML5