Refer this for 2nd Qn: http://ipassthecpaexam.com/cpa-international-students/
If you appear from US or Dubai cost is same, since theres is extra fees for appearing from UAE, i suggest to opt Dubai since you wont experience Jet lag there.
Job opportunities is very good, specially in Big4 in USA, if you work from USA you may get between $30K-$40K annually (non USA citizen). If you work from India then you may get annual package of 12-14 lacs.
Visit Miles CPA review center in Andheri, Times Square your all querries will get answered there. According to my review theie course structure is the best.
Thanks & all the best!