If you want to learn and be extremely productive at the same time, I'd definitely recommend to learn the
Ruby language and the
Ruby on Rails framework to build web applications, over PHP etc. As database system
PostgreSQL or
MySQL. It would be useful to learn also
Twitter Bootstrap o similar CSS frameworks (actually Bootstrap is more than just a CSS framework) to help quickly design responsive apps; then
Javascript and optionally
CoffeScript. With these tools you don't need anything particular to run a development environment; for the staging/production environment you can start first with something like the free tier of
Heroku so you can focus on learning the web development part first (Heroku takes care of the hosting part so you don't have to worry about it; it also takes care of the scalability if you decide to go with it also for the production environment).
Once you are OK with the development, you can avoid the expensive Heroku and learn to host everything yourself with, for example, virtual servers hosted by
Linode or similar; but there is a lot to learn there as well if you want to host your apps efficiently and securely.