Hi Big Ed, I can't help you on the Lincoln calipers.
I am not aware of carriers being any sort of weak link; the weak link is generally considered to be the diff cover housing that can flex under extreme load, thereby twisting the carrier and unit. the "weak carrier" is a symptom of the real issue, the weak cover/housing allowing the entire innards to move around inside.
Even in stock form though it is still extremely strong. Though our vehicles weigh much more than something like a YJ, failures are still almost unheard-of. Search this site for complaints of grenaded rear ends and the only ones you will find seem to be the ones that contained the old model ARBs. It was an ARB issue, not an 8.8 issue.
If you really plan on extreme hammering your Jeep, aftermarket diff covers that stiffen the housing and have bolts that hold against the carrier to strengthen the entire assembly are available.
If you have a 4.10 it probably has a TracLoc limited slip installed, which are much more effective than the "CrapLoc" TracLocs that come in Jeeps. 4.10 opens are out there but rare.
The electrical plug is probably the ABS unit, as you have guessed. However my '99 4.10 rear has its electronic VSS sensor there instead, so if your axle came from a '99 4x4 it very well may be the electronic VSS that functions as the speedometer sensor.