If you purchase above 500 rating you'll receive 50 bonus rating automatically to your target rating after the order is submitted. If you purchase at least 1000 rating you'll receive 125 bonus rating!
No the bonus rating doesn't stack if you purchase over 500 rating but under 1000 rating you'll only receive 50 bonus, if you order 1000 rating you'll receive 125 bonus rating. NOT 175!