Sharks are around all times of the year but winter tends to be better because lemon sharks migrate through. They will be gone by May, but plenty of reef sharks, nurse sharks, and bull sharks around, but cannot be guaranteed on any particular dive. However, you might see lots of turtles that time of year as it is just before nesting season.
Emerald runs an open-crate, bloody fish hand-feeding operation, in deep water (90' or 130" depending on site). No protective gear or protocols that I can see from posted videos. They sometimes actively spear fish in the area to draw sharks. Not my cup of tea (and I have done other shark feeds such as Stuart Cove's) but they have a local following. Certainly the most reliable way to see a shark around here, and by far the most dangerous.
Other charters will drop you on reefs where the current or previous day reports indicate sharks. These sharks, in "natural" conditions, will be more stand-offish and exhibit less excitable behavior, but, as I said, cannot be guaranteed on a particular dive.
Dive conditions range from 45' reefs to 100' deep wrecks. Some of the most beautiful reefs are 90' ledges off of Jupiter. Nitrox is best, by far. Current is usually present and moderate to strong. Drift diving is the norm. SMB is mandatory, as is a whistle. You can expect hot drops and drifting ascents where the boat will pick you up after you deploy your smb.. Vis is usually good, 50 typical to 100+ on some days. The reefs are not as big, colorful or lush as Cayman. No walls. But, the reefs host lots of big animals, and the wrecks, especially, host big animals including lots of goliath grouper and sometimes game fish.
Weather is unpredictable in April and May. Wind fronts can come through and create rough seas. You need to check conditions literally a day or two before a trio to see if you want to go out. Expect water temps in the high 70s to low 80s. A 3 mil is fine for most people.
as for trips, the "area" includes Boynton Beach, West Palm, and Jupiter. Some favorite trips"
Boynton: The Castor Wreck (must-do for goliath grouper) and any number of gorgeous shallow reefs. The main attractions on the reefs are turtles and long forests of soft corals and big sponges. Really nice, even if you are used to Cayman.
West Palm: Some nicer shallow reefs such as Ron's Rock. Turtles. Good wrecks are the Amaryllis and Governor's Riverwalk. Goliaths, turtles and often sharks here.
Jupiter: Wrecks: Zion (also called Wreck Trek) for goliaths and sharks; MG-111 for all sorts of critters and fish (60' for a good second dive). Deep reefs: Juno Ledge and Monkey Ledge--beautiful but 90' deep. Shallow reefs: Tunnels, a very bland ledge that never disappoints with turtles, sharks and goliaths, as well as big schools of fish.
Charter Boats (some are tied to shops):
Boynton: Splashdown Divers (also a small shop); Underwater Explorers
Palm Beach: Jim Abernethy (a shark expert)(also a shop); Pura Vida (also a shop); Narcosis Dive Charters
Jupiter: Jupiter Dive Center (large shop and two boats); Cap't Sl8r; Emerald (at your own risk).
If you are looking for a good shop not tied to a particular boat to coordinate for you, I recommend Force E in Riviera Beach and Scubaworks in Jupiter.