I tried Hittail a year ago, and didn't quite work for me. I ended up writing a few scripts myself.
But I heard in Rob's latest podcast that Hittail is growing 30% per month.
There are different levels of scaling, and for different kinds of apps, the trade offs that you can make are different.
Unless you are making a really huge leap, most of the time it will be a gradual process. So unless you are talking Google or Twitter Scale in a matter of months, it may not be as bad as it sounds.
Monitor, optimize your current configurations, cache, load balance, cluster, use messaging, use existing industry knowledge on distributed systems, read academic papers and innovate...
For advanced distributed systems, checkout Prof. Indranil Gupta's lectures amont many others:
http://www.cs.uiuc.edu/class/fa10/cs425/lectures.html
Groovy doesn't get enough press in HN but I would think Groovy is practically the most widely used of them all just because of Grails.
I prefer Scala when I am doing backend stuffs but use Groovy/Grails for web stuffs.
HTML, CSS, Javascript, browsers, database, IDE, at least one server side language, and hosting for a simple web app.
Web development sucks. We are just used to it.
Don't get into the Rails vs Django war. Just pick up any one of them and start coding. Both frameworks are highly productive and very easy to pick up.
If you go with Rails, you can use Heroku for hosting which is free to start with. If you go with Python, you can use Google Appengine, which is free as well for starters.
You can own or start a company, but you cannot work for it until you have proper authorization, ie. CPT, OPT, H1b, Green Card, etc. If you are found to be working for any company including your own, you could be out of status and hence deported. Thats my understanding.