Welcome to Linux.org!
To answer your 2nd question first, you can do software development in either, even OS X is popular at some companies. All modern OSes have tools to develop.
That being said, I believe it's more convenient to develop and code in Linux as it's likely the OS where the code will be running anyway once it's complete. This means you can test your code on your workstation in most cases, etc..
For your 2nd question, while there are a TON of differences between Windows and Linux, both look/feel similar. One big difference for Linux is that you can accomplish much more via command line. You'll find that most Linux users usually have at least one or two terminal windows open for various things.. for me it's for ssh sessions into remove Linux machines, for others it's for coding or tweaking settings on their system.
Also, software updates on Linux are a breeze compared to Windows.. you can either use a graphical interface to update or a quick command, then shoot it into the background. Also, with Windows, most times you're rebooting because something froze up, or updates just went through, etc.. Linux, you're really only rebooting if you do a kernel update..
Hope this helps!
Your next question should be which Linux Distribution is best for what you want to use it for!
Rob