The art board size for an image as large as you mentioned isn't typically built at the size that it will output. Instead, it's usually built at a fraction of it's actual output size, like maybe only a...
I used his practice files to create two sites in DW and everything went pretty well. I feel I got a good grasp on writing html, css and file organization. So whats the problem? The sites look good but my friends that I'm designing for need a content managing system so I went through 5 hours of tutorials on using wordpress.org at the same time I went back to lynda.com for some more tutorials on building wordpress themes using PS/notepad/wamp and so on... Then I started seeing all these really nice looking WP themes and thought oh sht!, this looks like a trap but so hard to resist.
So now Im here and feel super confused with all this info and want to know what route I should pursue.
Also want to add that I worked in PS and designed about 100+ works for the last 6 years without realizing that all my logos, flyers, ect. were a bit off due to bitmap ... btw, I'm also in another crash course learning Illy.
I don't want to travel down another road like that in webdesign.