First bloke - the "possessed" one - is having a panic attack. Like my poor DP does.
EVP - DP, being the genius he is, has just explained about different microphones (dictaphones pick up everything) and how it record things. (Eg. the sound of the dictaphones mechanics, the actual buzz of the electronics, and noises beyond human hearing) Which when recorded over multiple times layer and sound louder. Done enough times you could even hear radio noise - though severely distorted.
WRT picking up electronic noises, DP suggest putting headphones on and touching the jack to some ungrounded metal, then you'll hear a kind of static noise.
Those noises are so easily explained.
THe blessing - erm.. the relic.. really?!
The photos - the door is a reflection of the light. The face in the mist - oh come on!!
EVP again - note how Lou's voice is distorted, so of course the static is.
Ah.. and here's the aggression when cornered
EVP yet again.. that was wonderful. So they listen and respond to Lou, but refuse to listen to Derren.