veilside if u got a bin, its a start, chuck it in there..... na joking, if its a half bar, u fit it over ur old half bar and bolt on....
Sikaflex. A.K.A. Black tar from the very depths of hell (if you haven't used it before you will learn it's messy, but a great sealant / adhesive.) http://www.sika.com.au/cmc/Datasheets/pdf. You can purchase it from Bunnings or most auto stores.
Rear Bar What is wrong with it. Can you take some pics of it while on the car to see what the trouble is we may be able to help you through this.