Front End Alignment

[DirtDonk]

Do extended radius arms or even the T-Rex arms help add caster?

Sorry DD, didn't see this the last time around. Yes, that works too, similar to the other adding-parts methods.

Other than being able to gain more caster (which is a probably enough reason) is there any benefits of cut and turn vs. T-Rex arms.

Yes, the cut-n-turn is still the only way to gain caster without negatively impacting your pinion angle/u-joint clearance.
The radius arms are a great way to gain caster, and with some arms other benefits as well. Including strength, tire clearance (a big deal in my book) and some geometry improvements.
But they still tilt the axle to get the caster, which increases the pinion angle, which may put the u-joint in a bind. In addition to binding, u-joints of this style get progressively weaker the more angle they're forced to rotate at.
This is why you never jump on the gas pedal to get past an obstacle when the wheels are turned. Unless you just can't help it, and even then you should moderate your right foot to help the axle u-joints and axle shafts live longer. Same for the front driveshaft. If you need to put the power to the ground while the u-joint is at a severe angle, it's strength is seriously reduced.

The double-cardan style joints installed at the transfer case end of the driveshafts do improve on this a bit, but that does not help the single-cardan style joint that is at the center of this conversation.
I'm a big fan of longer radius arms. And I like the additional caster they have built in. As long as it does not impact the angle too much, and if you go back down to a 2 degree C bushing.
But sometimes it's just unavoidable depending on how the axle was built.

1. Anything else I should change while the axle is dropped and the radius arms are out?

At least use this opportunity to inspect the vent for clogs. You can do it any time of course, but with the axle down you can see into the port more easily and replace the bolt if it needs to be.
If you're not familiar, the venting is actually done through the retaining "bolt" that holds the hard brake lines to the axle, where the soft brake hose enters.
Always a good idea to make sure it's clear.

Other than that, all the usual previously scheduled maintenance can be performed if it hasn't already. Wheel bearings, ball joints, axle shaft u-joints, anything that's old and tired.

2. Should I switch to degreed radius arm bushings?

Depending on the lift (anything over 2.5") for a street driven truck, I'd say yes for sure.
If the replacement radius arms come with their own frame mounts, then no you don't need to. You simply install the mounts with the proper angle to allow the arm to enter at the proper angle.
If the radius arms use the original mounts, then it depends on the design of the arm. But generally anything you can do to make the entry to the frame bracket more natural, the better.
So if the accommodation is not built right into the arms, then the degreed bushings are a great addition.

Paul