It's entirely up to you whether or not you want to roach your horse's mane. She won't care either way.
Use clippers when roaching. You can't get close enough to the skin to do a good job with scissors.
This is true, and it will always grow back. I shall look up clippers on e-bay or see about borrowing some. And youtube a "how to" video. If I do a terrible job it shouldn't matter, we're just happy hackers :)
I'll post the video's I find here for others to see.
Roaching is pretty easy, since you're cutting everything off down to the skin. I had to roach my Arabian's mane once, as he'd rubbed out a whole section right in the middle. He looked pretty good, even though my other Arabian owning friends were horrified!
I always get paranoid when using clippers (never clipped a horse. Just my dog and giving the odd haircut to friends) When I was little my brother used to clip our dog and he'd tell me "it takes skill, if you're not careful you'll clip her skin off instead." Because I was young and impressionable that fear of skinning things using clippers has stayed with me even though its ridiculous!
I roached my boy's mane about a month ago because he would sweat underneath it. My friend calls him Sgt. Because he looks like he belongs in the Army now :) And I roached it ALL, hehe
I love it though!!