Diving the east coast of UAE, along the Gulf of Oman, is much better than the west coast. The east coast has better visibility and lower salinity. You will not have to wear as many weights, making it more comfortable. You will have better clarity to enjoy the critters you see. And simply put, there will be more variety and density of fish life.
All hotels in the area will offer dives and can coordinate. I cannot recommend any one specific over the others. Al Boom Diving (contact info below) is located in Dubai, but will offer transportation and connection to dive from Le Meridien Resort Fujairah (which is actually closer to Diba).
If you have any control over it, try to dive further north. The further up the coast line you get, the better the diving. If you make it into Musandam Oman, you will have reached the best diving in this coast line.
Equipment: Bring your own if you have it. All dive shops here have full equipment of good quality.
Very good dives can be had from Fujairah. Now that I've been to Oman, I can say that the viz in Fujairah was much better. Masses of fish everywhere.
I loved it and the water was very warm (27 to 32 celcius depending on depth in June, with a nasty thermocline!).
Diving is much better than on the Gulf side (Dubai). The viz is approx 10 to 20 metres.
Equipment: I used my own equipment but you can get the gear from any local centre