Just a bit of coroberation to Big Jim's reply
Is the shock tippet just heavy line, i.e. bite tippet?
Yes. I just use 60lb Seaguar flouor for big tarpon. If you are coming down in the winter, I'd drop down to 40 lb.
Also, would 30lb. nylon coated steel (Steelon) work for small sharks and mackerel?
I've never used anything but single strand stainless wire in coffee color (standard for Malin brand), with a haywire twist to the hook and an Albright on the other side. Spanish Macs can be leader shy in clear water if they're not excited, so if they're around and won't take the fly, I'd just can the wire, use a fairly long steamer and hope for the best.
I would use #3 Malin for them (31 lb test) . The strength is roughly 10 lbs x the number in the lighter wires. It's available about everywhere and cost is about $3 per 40 ft. coil (smallest length).
Kingfish (king mackerel) will definitely require wire. They, however, are a less likely target for the fly unless they are busting bait on the surface. In the keys they ocassionally come up onto the reef in 15' of water but usually hang mid to lower 1/3 of the water column in 100-120 feet of water. They do get big though, and will scream an 8 or 9 wt.
Blacktips are usually finiky in clear water and actually pretty delicate eaters, and will generally track behind the fly for a long time. The best luck I've had is with a long cast, and once they start tracking, keeping the fly a foot in front of their nose with a steady retrieve. I'd use #5 for blacktips and lemons.
Bonnets are usually very agressive, if around, and will usually attack anything brainlessly, as many bonefishermen have discovered.
They often hang around areas with muddy bottoms as well as flats. They put up a good fight on light tackle but are small and don't jump like blacktips often do.
Incidentally, both spanish and cero macs will be around and cero's in particular can easily get to 12 lbs or so. Both are actually excellent eating if thrown immediately into ice with salt water - like all fish - including small blackfins. Their blood will go out of their flesh to their vital organs this way (just as ours does with hypothermia) and is better than trying to bleed them.
They should be eaten no later than the next day and not frozen. I put the filets into plastic bags with a little bit of orange juice and immediately refrigerate. They are not oily or strong tasting if handled this way and eaten the day following catching them. They don't taste like oranges either.