gel caps are ok to take as long as its the kind with only dxm in it, youll proberly puke a little bit but nothing to worry about.
id say a bottle and a half to 2 bottles for a decent trip, each bottle of gels has 20 pills with 15mg of dxm each. so any where from 300mg-600mg for a good trip, i however suggest 30 pills which is 450mg.