Default Output Device is always wrong
First of all, I'll address the how to uninstall Soundflower problem:

A number of people have run into problems uninstalling it in the past. The main problem seems to be that you have to reboot your machine after running the uninstaller but if that doesn't work for you try removing it from the Audio MIDI setup. 

Open Audio MIDI Setup in the utilities folder and look for Soundflower listed there, select it and click the minus near the bottom left to remove it.



Now that you've removed Soundflower, you need to set the headphones as your default output device:


Connect your headphones
Open System Preferences and Open the "Sound" panel
Go to the "Output" tab
Select your headphones here
Close system preferences


Your system should now default to the headphones whenever you plug them in.



If you run into further problems, you can try a couple of advanced steps:


Open Finder and in the "Go" menu, select "Go to Folder..."
Type ~/Library/Preferences and click Go
Locate two files called com.apple.systempreferences.plist and com.apple.audio.AudioMIDISetup.plist and move them both to the trash
Reboot your computer
If you're still having problems reset PRAM by rebooting again and holding command-option-p-r as soon as your computer boots up, keep holding until your computer restarts again and you hear the startup chime.


Follow all the above steps from the beginning of this post and one of them should solve your problem, make sure you check each time if your headphones are now working by default.