There is no tax in the UAE, however there may be some form of shipping tax applied to get your kit in.
I live in Dubai and I can confirm that we have various shops that sell most of the gear you mention, Grand Stores in the Mirdiff City Centre mall have Bowens Lighting gear, Al Falak and Kansas will be able to help you out too, and I’m pretty sure that Micro have a lot of studio kit available.
Prices are actually slightly cheaper here for the lower end user products, the newest Canon 70D is currently selling with the 18-135 STM kit lens for around $100 less than the B&H list price.
Here are Telephone details for the best stores in town, all can be found in Mirdiff City Centre.
Al Falak, 1st floor, Tel: 00971 4 284 0801
Grand Stores, ground floor, Tel: 00971 4 284 3055
Canon, 1st floor, Tel: 00971 4 284 3312
Kansas, 1st floor, Tel: 00971 4 284 3655
Micro, 1st floor, Tel: 00971 4 252 4251