SEO, SEM, web design, coding, iPhone, iPad, Android 

I've been using Consolas for a while now and have been really happy with it. I especially like how the curly braces and semicolons are easily distinguishable.

Check out web monkey as they have a ton of tutorials on javascript, html, css and other web and programming related things.

I'd also suggest snagging a copy of DOM Scripting by Jeremy Keith if you're in the market for a solid book to read.

I stick with a basic monospace on Linux -- works out well for me.

AdrianL said it well. Accessibility is a function of your website, not something that can be added as a feature of sorts. You can create an accessible website by using standard markup and following best practices that produce accessible documents. Your best bet is to read quality articles regarding accessibility and then evaluate your site, making improvements where applicable.

What's more important is to use ins and del for their semantic purpose as opposed to their rendering on screen. Different browsers will more than likely have different ways of styling elements by default which is always important to keep in mind :)

I'll go along with both previous posts. You can't really go wrong with focusing your efforts on the combination of PHP & MySQL. That doesn't mean that after you've taken some time with something, you can't explore other areas out of curiosity. There is choice when it comes to programming languages because they're suited for different people and different tasks.

I'd say get more of a grasp on XHTML and CSS.

I'll echo what frotzed said.

PHP / MySQL or find a business partner that knows them like I did.

You can always give ruby on rails a whirl if you want to explore that realm.

I'd go for php and mysql. I have a cursory knowledge of both, but am an expert in neither. I find myself often thinking to myself, "man, I wish I knew php better and mysql better." I've never said, "I wish I knew Ruby." There have been times when I wished I knew Javascript better, but it's less frequent than php and mysql. Just my two cents.