Scarecrow overcame all his fears [cept for his almost sexual need to seek out Batman] but he was exposed to his fear inducing toxins too much and it was a side effect. [sorry, LOVE Scarecrow]
fear is something you must learn to overcome, you could try hypnotherapy, but mnostly it's a personal journey. in regards to AP, your body isn't in any danger of a demon attack, the second anything threatens it, you're zapped back into it. while you're in the astral, yes, your astral self could be attacked [cuz now all the astral beings are like physical beings] but that doesn't happen unless you're going out of your way. when i project, i go to a secluded valley where dragons dwell. i've never come across another being but dragons, so unless you seek them out, i doubt you'll find one waiting to pounce you.
coming back, there are no documented cases of astral selves getting lost. in the ethral you are attached to your body with a fine string, in the astral, you merely think of your body and you're back.