I havent had a chance to finish editing my video, but I made a youtube video for this. I go over setting up a pooling manager (spawner and despawner), cover gameobjects, sounds and particle effects I think.
I should have it posted to my youtube channel in the next few days. In the meantime, I suggest pooly as the best solution (and the one I use in my tutorial video). Price is right, its easy to use, it comes with a playmaker instruction video (short and less detailed than mine but it will get you started) and the dev has been responsive.
https://www.assetstore.unity3d.com/en/#!/content/82941Pooled objects need to be the same object. Ie, 10 of the same enemy, sounds, particle effects, etc.