Congratulations on the new job! I don't mean to rain on the parade, but keep in mind that "free" music downloads are usually illegal, and we strongly discourage it on this site. Besides, downloading from those kinds of sites is a good way to catch some malware! But check out
Amazon's MP3 Store frequently, because they often have good deals on songs and albums, as well as some free songs. Also check out
Google Play Music frequently for the same reason.
There are so many excellent music players on Google Play, most of them free. In no particular order, there's
PowerAmp,
Winamp,
DoubleTwist,
MixZing,
Mortplayer--and the list goes on. Since most are free or free to try, give them all a whirl and see which one works best for you. Personally, I think Google Music works just fine.
Phone cameras are always going to be relatively inferior to standalone cameras, especially when it comes to shutter speed. Fortunately, the Samsung phones are known to have above-average cameras. You could try
Camera Zoom FX, which has a nice stability feature--it won't take the shot until the phone is completely stable, resulting in less motion blur. It does cost $2.99, though.
For pictures, I like
QuickPic--it's a good, lightweight replacement for the stock Gallery, and has a nice user interface. It's also free!
For keeping your phone running in top shape,
All-in-One Toolbox can be handy to clear the temporary caches of all of your apps and see what apps are using most of your battery. To get the most out of your battery, refer to this guide:
http://forums.androidcentral.com/general-help-how/298919-guide-battery-saving-tips.html
Above all, enjoy! Android just keeps getting better and better.