I used Melon.js for the client. Very easy to start with that. Excellent support was offered for free. I'd recommend it for beginners. For the server I used CometD/BayeuxServer/Jetty.

The artwork was royalty free. You can see the credits on the home page. All of the levels were generated with code I wrote. It took awhile for me to write it in my spare time, but now that I know what goes into a game it would be much faster to write again. There was plenty of trial and error. With something like this, you need to experiment around to find what works. I personally was new to writing heavier JS apps and had experience with Java based webapps. The tools you choose maybe different. I can't say that any language or tool is the best, but I liked these options. I'm happy with my choices for the tech.

Hope this helps you. I wouldn't worry about the specifics of technology used. These are actually very minor details. On the computer there is a solution for most any problem you will approach.

Instead focus on bringing a project to completion. Persistence and stamina are the most important ingredients. It also helps if you can break your project down into manageable pieces, so you can approach it step by step. Look at the number of people who never finish their projects. This is a bigger hurdle than any technical issue.