The Brothers itinerary is usually 18 dives on a week long Liveaboard as night dives as not permitted on some of the dive sites. 50 dives is a prerequisite experience level for booking on the trip, not the number of dives on the trip itself. All Red Sea operators will carry out an easy 'check' dive first so divers can settle in, do weight checks, etc. Also an opportunity for the guides to discreetly asses everyone's ability level. Great trip by the way, you'll have a blast!
Anyone worried about inquisitive sharks, just take me along! I garauntee there won't be one for 50 miles as I'm probably the unluckiest shark spotter out there.