Everything you describe is normal. It will not scare girls off. Some kids in your school at your age and even younger might have a lot more hair then what you have on your body.
The hair is not a problem; some men have a lot, while others have a little. Every body different. You could see your doctor or a dermatologist about the acne.
Normal! All normal! You will find out that there are also ladies out there who like a hairy chest and arse as you call it. Difference in being a boy or a man! If it offends you, you can always have it removed.
For the back acne, plain white vinegar should help with that. It was recommended on the show, The Doctors.