Are you on a Mac or a PC?
No. You can only open one instance of same application and version at one time. I know of no application that will allow that. At least not on a Mac.
And no. DreamWeaver is not a word processor for webcode. That's a very simplistic way of looking at it.
And no, it cannot highlight misspelled words on the page. At least not on a Mac.
I am PC.
And YES, as lame as it is, ALL versions of MS Front Page, and now all versions of EW open as many instances of the program as you need.
And YES, as lame as it is, ALL versions of Front Page, and now EW do spell check like a word processor. Being able to see a comon (<--like this) mistake with red underlines makes it so easy to correct at a glance. It is absolutely necessary when you work with text-based content.
When you post here on this fourm, notice that beautiful ABC button up there in the right corner that when clicked, it shows the errors underlined on the page. That's ALL I'm asking for. Not too much to ask. I don't want to have to SHIFT F7 and mill through the whole page one mistake at a time in a dialouge box. I want to see the red squggly lines at a glance for the whole page. Try doing that with a document that is full of scientific terms!
I worked with FP since 1995 when I started on the web, and then into EW. But the company that I work for "frowns" on EW. So I am stuck with DW. Don't get me wrong, it is a beautiful editor (and YES, in it's simplistic form, it IS a word processor) and does so many slick and wonderful things. Admittedly, it does make my life easier.
But the basic functions that would make my life easier, such as multiple instances of the program and a very simple spell-check-as-you-go feature is really not asking too much.
Not everyone that's working on the web is slinging around cutting edge stuff, and using all of the bells and whistles DW offers. There some of us who are working in a CMS with templates who need a robust html editor, but also the features of a robust word processor as well.
For the deep cost of DW, I don't think that is too much to ask.