You have been pointed in the right direction to find the answers to your questions but I wanted to add some quick reference info on the cat.

Royal Canin will soon be available here in Doha but for now yes you can get IAMS/Eukanuba.

To find all the information you need regarding bringing the cat here with you check out www.qatarpetrelocators.com or www.qaws.org

Everything you have listed above is available, though sometimes more expensive as imported goods always are. Follow the threads on the preparations and set up forum, cost of living etc.... as Sammie said above, all of this should be covered there.