Here is a good video on how to gently pull a mane. You cut a long mane then slowly start pulling to get it short and even. I like my mane so the length is about the width of my hand
And yes, leave her forelock! Its beautiful and can be braided easily. I am going to be doing a how to braid video soon as i've been getting people bugging me lol. I have a nice way of doing the forelock so it looks neat and tucked without sticking up like a unicorn horn lol.