Livelining from a boat
the old K.I.S.S., Keep It Simple Stupid, is the best approach. I recommend a Fish Finder rig
with a leader length of 36 inches although some guys use 48 to 60 inches. Hopefully you have an electronic depth finder/ fish finder which can display any fish and what level in the water column they are stacked. Natural humps are a favorite hang out for most fish.
If the fish are hugging the bottom you will want to use a fish finder slide with an attached bank sinker to keep your bait down. Normally a bank sinker of just a few ounces is fine unless the ocean swell is rocking the boat hard. If the fish are suspended in the water column eliminate the sinker or use one just heavy enough to keep the live bait below the surface.
Personally I prefer drifting rather than anchoring the boat but I always prefer using Gamakatsu 8/0 Circle hooks. Second choice Octopus hooks. With Octopus hooks you have to use a size that works with the bait but is not so big that it will kill it. Nothing less than 6/0, but 8/0 is the optimum size. Using Mullet, size 8/0 may be problematic since they are relatively "delicate."
BTW I do NOT like "Live Bait hooks," for two reasons, first they are thicker and kill your bait and second most of them have a straight shank and eye which is not ideal for snelling. A bent back eye works better with a snell knot and your pull on the hook will be direct. (straight Hook diagram HERE
With any hook, and bait always be sure that the BARB is exposed - that is critical for Circle hooks.
The reason why I prefer Circle hooks from a boat is that they are "forgiving" since it usually difficult to "feel" a fish sucking in the bait. Consider that you may have a lot of line out in the water; the boats rocking, the wind is blowing and the current is pulling, add that all up and your "feel" is diminished (note depthfinder/fishfinder image above - depth is 101 feet!)
Livelining in the surf or from a jetty
is trickier because you have to cast and then contend with the incoming swell and waves. You are an experienced fisherman so I know that you will agree that "casting" live bait in the surf is better described as "softly lobbing your bait." Here I also use Fish Finder rigs, but no longer than 24 inches and only with Octopus hooks, 6/0 minimum, 8/0 ideal (using big chunks or a large live bait like Menhaden I prefer 9/0 or 10/0 hooks).
Use a pyramid or Hatteras sinker on the fish finder slide; weight depends on surf conditions - swell, current, rough water etc.
Another rig that works well for livelining in the surf is the SlapShot rig
with a 9 or 12 inch leader. This rig keeps your bait at the bottom where most fish in the surf will be located. I ship a mess of SlapShot rigs to customers in November and December who fish the Outer Banks for striped bass.