Fallen Angels, Nephilim, Principalities, Powers or Rulers in the Second Heavens?

Who are the cosmic beings we come against wearing the pieces of armor in Ephesians 6?  Who are the fallen angel world forces of darkness and spiritual forces of wickedness in the second heavens?  How do we use our offensive weapons to defeat demons and how do we rebuke demonic kings in Jesus" Name?  How do you close doors to cosmic beings who attack on a daily basis? Are there Nephilim or hybrids on earth today?  How do you discern what is just a demon versus a fallen angel?  How much power does satan have?  Is he ever in control?