I'm not sure why it's not recognising the device as mtp device. It should have no problem seeing it as both adb and mtp. My guess is that it has something to do with the driver for mtp not being set up properly since being configured for adb. As for rooting the device, congrats on getting it to work and opening the door to more freedom with your device. Now that you're rooted, you essentially have administrator privileges on your device. This will allow you to run some apps that you didn't have access to earlier such as Titanium Backup which allows you to backup as well as restore all your apps. Another common app is AdFree or another app of that nature that allows you to block most of those pesky ads you see in your apps. Other interesting things you can do is with root + custom recovery (twrp), you now have the ability to run custom roms and/or kernel on your device that can allow you to better performance or appearance.