chances are higher because of the fertiltly drugs, however I to have PCOS, and was advised by my RE that clomid is very bad for PCOS patients because after taking for more than two months it actually causes your body to make cysts so please be careful when taking this drug. Fumera and Follistem together is a better drugs for PCOS patients, as long as there is careful monitering. Good Luck maybe your first try will work. (my first try with Clomid worked however I miscarried at 4-5 weeks)
I dont know the percentages but there is slitly more of a chance that you can have twins than you would without it only cuz clomid makes you produce multiple eggs instead of just one. The chances of more than two are less likely. Good luck