AppEngine is great, and the language really depends on how much of a scalability you want. Ruby can be a great thing, since with Rails already has great implementation for writing REST APIs fast and scalable.
Usually I use a combination of AWS, NodeJS and Parse for the better stuff like Push...
Use console.log to DEBUG your output. If you wan't to output it to the DOM (the HTML page) you'll need to iterator using a for-loop. I gave you the answer above.
And by the way. Put your HTML and script tag in the <body> tag. The script should be the last in <body> tag.
Don't use document.write - it's bad, slow and really stupid. If you wan't to do DOM manipulation the easiest thing to do is using jQuery.
Now for your problem: You cannot write out JavaScript objects, arrays and like to the DOM. The DOM doesn't understand that kind of stuff. If you wan't to see...
Ruby is similar to Python on the behalf that it is an indention based language. However, it requires a little more knowlegde of Ruby and how it all works. It can do amazing things and has amazing way of making structured applications with easy API.
However, again I recommend you to look at it...
It really depends on what you're going to do with it. If you're going to do web or similar, Python is a good way. If you want to do games or a like you could stick with Java. It's really what you're most comfortable with. Also since the syntax is very different from each other, that is a factor...
Python is fantastic easy to learn, and you can learn it straight from the site at http://python.org/doc/ - also if you wan't to learn it the hard way http://learnpythonthehardway.org/book/ is a good choice.
Need to learn other languages the hard way? Head over to http://learncodethehardway.org/
I started when I was about 11 years old - using mspaint, Frontpage and horrible framesets in XHTML. Didn't know anything about anything else. Back in the days there werent YouTube so I basically googled (which is how I learned how to search on Google, the right way) me the way through HTML, CSS...
But if you're going to learn MySQL anyway start at a point where you don't use old functions.
You should NEVER rely on string data. I could change the hidden field anyway I wan't and submit it (even with malicious code, which MySQL can't escape - read about XSS). Therefore you should use IDs to...
First off, use MySQLi or PDO instead of the old mysql functions (they're deprecated in newer versions of PHP).
To find 'reply' in a string you can do something like
$postTitle = "Reply: Hello World";
if (strpos($postTitle, 'reply') !== false) {
// Do something if reply is in string.
}...